feat(tool): conditional description for read file

CHANGELOG.md

@@ -11,6 +11,8 @@ Only write entries that are worth mentioning to users.
 
 ## Unreleased
 
+- Tool: Make `ReadFile` tool description reflect model capabilities for image/video support
+
 ## 0.75 (2026-01-09)
 
 - Tool: Improve `ReadFile` tool description

Makefile

@@ -110,9 +110,9 @@ ai-test: ## Run the test suite with Kimi CLI.
 .PHONY: gen-changelog gen-docs
 gen-changelog: ## Generate changelog with Kimi CLI.
 	@echo "==> Generating changelog"
-	@uv run kimi -c "$$(cat ./docs/prompts/gen-changelog.txt)" --yolo
+	@uv run kimi -c "$$(cat .kimi/prompts/gen-changelog.md)" --yolo
 gen-docs: ## Generate user docs with Kimi CLI.
 	@echo "==> Generating user docs"
-	@uv run kimi -c "$$(cat ./docs/prompts/gen-docs.txt)" --yolo
+	@uv run kimi -c "$$(cat .kimi/prompts/gen-docs.md)" --yolo
 
 include src/kimi_cli/deps/Makefile

docs/en/release-notes/changelog.md

@@ -4,6 +4,8 @@ This page documents the changes in each Kimi CLI release.
 
 ## Unreleased
 
+- Tool: Make `ReadFile` tool description reflect model capabilities for image/video support
+
 ## 0.75 (2026-01-09)
 
 - Tool: Improve `ReadFile` tool description

docs/zh/release-notes/changelog.md

@@ -4,6 +4,8 @@
 
 ## 未发布
 
+- Tool：让 `ReadFile` 工具描述根据模型能力动态反映图片/视频支持情况
+
 ## 0.75 (2026-01-09)
 
 - Tool：改进 `ReadFile` 工具描述

pyproject.toml

@@ -28,6 +28,7 @@ dependencies = [
     "pykaos==0.6.0",
     "batrachian-toad==0.5.23; python_version >= \"3.14\"",
     "tomlkit==0.13.3",
+    "jinja2==3.1.4",
 ]
 
 [dependency-groups]

src/kimi_cli/tools/file/read.md

@@ -13,6 +13,20 @@ Read content from a file.
   - Use `line_offset` and `n_lines` parameters when you only need to read a part of the file.
   - The maximum number of lines that can be read at once is ${MAX_LINES}.
   - Any lines longer than ${MAX_LINE_LENGTH} characters will be truncated, ending with "...".
+{% if "image_in" in capabilities and "video_in" in capabilities %}
 - For image and video files:
-  - Content will be returned in a form that you can view and understand. If you do not support image/video input, try other tools to process media files.
+  - Content will be returned in a form that you can view and understand. Feel confident to read image/video files with this tool.
   - The maximum size that can be read is ${MAX_MEDIA_BYTES} bytes. An error will be returned if the file is larger than this limit.
+{% elif "image_in" in capabilities %}
+- For image files:
+  - Content will be returned in a form that you can view and understand. Feel confident to read image files with this tool.
+  - The maximum size that can be read is ${MAX_MEDIA_BYTES} bytes. An error will be returned if the file is larger than this limit.
+- Other media files (e.g., video, PDFs) are not supported by this tool. Use other proper tools to process them.
+{% elif "video_in" in capabilities %}
+- For video files:
+  - Content will be returned in a form that you can view and understand. Feel confident to read video files with this tool.
+  - The maximum size that can be read is ${MAX_MEDIA_BYTES} bytes. An error will be returned if the file is larger than this limit.
+- Other media files (e.g., image, PDFs) are not supported by this tool. Use other proper tools to process them.
+{% else %}
+- Media files (e.g., image, video, PDFs) are not supported by this tool. Use other proper tools to process them.
+{% endif %}

src/kimi_cli/tools/file/read.py

@@ -6,9 +6,9 @@
 from kosong.tooling import CallableTool2, ToolError, ToolOk, ToolReturnValue
 from pydantic import BaseModel, Field
 
-from kimi_cli.soul.agent import BuiltinSystemPromptArgs
+from kimi_cli.soul.agent import Runtime
 from kimi_cli.tools.file.utils import MEDIA_SNIFF_BYTES, FileType, detect_file_type
-from kimi_cli.tools.utils import load_desc, truncate_line
+from kimi_cli.tools.utils import load_desc_jinja, truncate_line
 from kimi_cli.utils.path import is_within_directory
 from kimi_cli.wire.types import ImageURLPart, VideoURLPart
 
@@ -52,20 +52,22 @@ class Params(BaseModel):
 
 class ReadFile(CallableTool2[Params]):
     name: str = "ReadFile"
-    description: str = load_desc(
-        Path(__file__).parent / "read.md",
-        {
-            "MAX_LINES": str(MAX_LINES),
-            "MAX_LINE_LENGTH": str(MAX_LINE_LENGTH),
-            "MAX_BYTES": str(MAX_BYTES),
-            "MAX_MEDIA_BYTES": str(MAX_MEDIA_BYTES),
-        },
-    )
     params: type[Params] = Params
 
-    def __init__(self, builtin_args: BuiltinSystemPromptArgs) -> None:
-        super().__init__()
-        self._work_dir = builtin_args.KIMI_WORK_DIR
+    def __init__(self, runtime: Runtime) -> None:
+        capabilities = runtime.llm.capabilities if runtime.llm else set[str]()
+        description = load_desc_jinja(
+            Path(__file__).parent / "read.md",
+            {
+                "MAX_LINES": MAX_LINES,
+                "MAX_LINE_LENGTH": MAX_LINE_LENGTH,
+                "MAX_BYTES": MAX_BYTES,
+                "MAX_MEDIA_BYTES": MAX_MEDIA_BYTES,
+                "capabilities": capabilities,
+            },
+        )
+        super().__init__(description=description)
+        self._work_dir = runtime.builtin_args.KIMI_WORK_DIR
 
     async def _validate_path(self, path: KaosPath) -> ToolError | None:
         """Validate that the path is safe to read."""

src/kimi_cli/tools/utils.py

@@ -2,6 +2,7 @@
 import string
 from pathlib import Path
 
+from jinja2 import Environment
 from kosong.tooling import BriefDisplayBlock, DisplayBlock, ToolError, ToolReturnValue
 from kosong.utils.typing import JsonType
 
@@ -14,6 +15,21 @@ def load_desc(path: Path, substitutions: dict[str, str] | None = None) -> str:
     return description
 
 
+def load_desc_jinja(path: Path, context: dict[str, object] | None = None) -> str:
+    """Load a tool description from a file, rendered via Jinja2."""
+    description = path.read_text(encoding="utf-8")
+    env = Environment(
+        autoescape=False,
+        keep_trailing_newline=True,
+        lstrip_blocks=True,
+        trim_blocks=True,
+        variable_start_string="${",
+        variable_end_string="}",
+    )
+    template = env.from_string(description)
+    return template.render(context or {})
+
+
 def truncate_line(line: str, max_length: int, marker: str = "...") -> str:
     """
     Truncate a line if it exceeds `max_length`, preserving the beginning and the line break.

tests/conftest.py

@@ -18,7 +18,7 @@
 from pydantic import SecretStr
 
 from kimi_cli.config import Config, MoonshotSearchConfig, get_default_config
-from kimi_cli.llm import LLM
+from kimi_cli.llm import ALL_MODEL_CAPABILITIES, LLM
 from kimi_cli.metadata import WorkDirMeta
 from kimi_cli.session import Session
 from kimi_cli.soul.agent import Agent, BuiltinSystemPromptArgs, LaborMarket, Runtime
@@ -58,7 +58,7 @@ def llm() -> LLM:
     return LLM(
         chat_provider=MockChatProvider([]),
         max_context_size=100_000,
-        capabilities=set(),
+        capabilities=ALL_MODEL_CAPABILITIES,
     )
 
 
@@ -242,9 +242,9 @@ def shell_tool(approval: Approval, environment: Environment) -> Generator[Shell]
 
 
 @pytest.fixture
-def read_file_tool(builtin_args: BuiltinSystemPromptArgs) -> ReadFile:
+def read_file_tool(runtime: Runtime) -> ReadFile:
     """Create a ReadFile tool instance."""
-    return ReadFile(builtin_args)
+    return ReadFile(runtime)
 
 
 @pytest.fixture

tests/test_default_agent.py

@@ -320,7 +320,7 @@ async def test_default_agent(runtime: Runtime):
   - The maximum number of lines that can be read at once is 1000.
   - Any lines longer than 2000 characters will be truncated, ending with "...".
 - For image and video files:
-  - Content will be returned in a form that you can view and understand. If you do not support image/video input, try other tools to process media files.
+  - Content will be returned in a form that you can view and understand. Feel confident to read image/video files with this tool.
   - The maximum size that can be read is 83886080 bytes. An error will be returned if the file is larger than this limit.
 """,
                 parameters={

tests/test_read_file_desc.py

@@ -0,0 +1,124 @@
+from __future__ import annotations
+from typing import cast
+
+# ruff: noqa
+
+import pytest
+from inline_snapshot import snapshot
+
+from kimi_cli.llm import ModelCapability
+from kimi_cli.soul.agent import Runtime
+from kimi_cli.tools.file.read import ReadFile
+
+
+@pytest.mark.parametrize(
+    ("capabilities", "expected"),
+    [
+        (
+            {"image_in", "video_in"},
+            snapshot(
+                """\
+Read content from a file.
+
+**Tips:**
+- Make sure you follow the description of each tool parameter.
+- A `<system>` tag will be given before the read file content.
+- The system will notify you when there is anything wrong when reading the file.
+- This tool is a tool that you typically want to use in parallel. Always read multiple files in one response when possible.
+- This tool can only read text, image and video files. To list directories, you must use the Glob tool or `ls` command via the Shell tool. To read other file types, use appropriate commands via the Shell tool.
+- If the file doesn't exist or path is invalid, an error will be returned.
+- If you want to search for a certain content/pattern, prefer Grep tool over ReadFile.
+- For text files:
+  - Content will be returned with a line number before each line like `cat -n` format.
+  - Use `line_offset` and `n_lines` parameters when you only need to read a part of the file.
+  - The maximum number of lines that can be read at once is 1000.
+  - Any lines longer than 2000 characters will be truncated, ending with "...".
+- For image and video files:
+  - Content will be returned in a form that you can view and understand. Feel confident to read image/video files with this tool.
+  - The maximum size that can be read is 83886080 bytes. An error will be returned if the file is larger than this limit.
+"""
+            ),
+        ),
+        (
+            {"image_in"},
+            snapshot(
+                """\
+Read content from a file.
+
+**Tips:**
+- Make sure you follow the description of each tool parameter.
+- A `<system>` tag will be given before the read file content.
+- The system will notify you when there is anything wrong when reading the file.
+- This tool is a tool that you typically want to use in parallel. Always read multiple files in one response when possible.
+- This tool can only read text, image and video files. To list directories, you must use the Glob tool or `ls` command via the Shell tool. To read other file types, use appropriate commands via the Shell tool.
+- If the file doesn't exist or path is invalid, an error will be returned.
+- If you want to search for a certain content/pattern, prefer Grep tool over ReadFile.
+- For text files:
+  - Content will be returned with a line number before each line like `cat -n` format.
+  - Use `line_offset` and `n_lines` parameters when you only need to read a part of the file.
+  - The maximum number of lines that can be read at once is 1000.
+  - Any lines longer than 2000 characters will be truncated, ending with "...".
+- For image files:
+  - Content will be returned in a form that you can view and understand. Feel confident to read image files with this tool.
+  - The maximum size that can be read is 83886080 bytes. An error will be returned if the file is larger than this limit.
+- Other media files (e.g., video, PDFs) are not supported by this tool. Use other proper tools to process them.
+"""
+            ),
+        ),
+        (
+            {"video_in"},
+            snapshot(
+                """\
+Read content from a file.
+
+**Tips:**
+- Make sure you follow the description of each tool parameter.
+- A `<system>` tag will be given before the read file content.
+- The system will notify you when there is anything wrong when reading the file.
+- This tool is a tool that you typically want to use in parallel. Always read multiple files in one response when possible.
+- This tool can only read text, image and video files. To list directories, you must use the Glob tool or `ls` command via the Shell tool. To read other file types, use appropriate commands via the Shell tool.
+- If the file doesn't exist or path is invalid, an error will be returned.
+- If you want to search for a certain content/pattern, prefer Grep tool over ReadFile.
+- For text files:
+  - Content will be returned with a line number before each line like `cat -n` format.
+  - Use `line_offset` and `n_lines` parameters when you only need to read a part of the file.
+  - The maximum number of lines that can be read at once is 1000.
+  - Any lines longer than 2000 characters will be truncated, ending with "...".
+- For video files:
+  - Content will be returned in a form that you can view and understand. Feel confident to read video files with this tool.
+  - The maximum size that can be read is 83886080 bytes. An error will be returned if the file is larger than this limit.
+- Other media files (e.g., image, PDFs) are not supported by this tool. Use other proper tools to process them.
+"""
+            ),
+        ),
+        (
+            set(),
+            snapshot(
+                """\
+Read content from a file.
+
+**Tips:**
+- Make sure you follow the description of each tool parameter.
+- A `<system>` tag will be given before the read file content.
+- The system will notify you when there is anything wrong when reading the file.
+- This tool is a tool that you typically want to use in parallel. Always read multiple files in one response when possible.
+- This tool can only read text, image and video files. To list directories, you must use the Glob tool or `ls` command via the Shell tool. To read other file types, use appropriate commands via the Shell tool.
+- If the file doesn't exist or path is invalid, an error will be returned.
+- If you want to search for a certain content/pattern, prefer Grep tool over ReadFile.
+- For text files:
+  - Content will be returned with a line number before each line like `cat -n` format.
+  - Use `line_offset` and `n_lines` parameters when you only need to read a part of the file.
+  - The maximum number of lines that can be read at once is 1000.
+  - Any lines longer than 2000 characters will be truncated, ending with "...".
+- Media files (e.g., image, video, PDFs) are not supported by this tool. Use other proper tools to process them.
+"""
+            ),
+        ),
+    ],
+)
+def test_read_file_description_by_capabilities(
+    runtime: Runtime, capabilities: set[str], expected: str
+) -> None:
+    assert runtime.llm is not None
+    runtime.llm.capabilities = cast(set[ModelCapability], capabilities)
+    assert ReadFile(runtime).base.description == expected

tests/test_tool_descriptions.py

@@ -188,7 +188,7 @@ def test_read_file_description(read_file_tool: ReadFile):
   - The maximum number of lines that can be read at once is 1000.
   - Any lines longer than 2000 characters will be truncated, ending with "...".
 - For image and video files:
-  - Content will be returned in a form that you can view and understand. If you do not support image/video input, try other tools to process media files.
+  - Content will be returned in a form that you can view and understand. Feel confident to read image/video files with this tool.
   - The maximum size that can be read is 83886080 bytes. An error will be returned if the file is larger than this limit.
 """
     )