校验本地图片

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, and the description adds meaningful behavioral context beyond those: no network access, no file modification, and validation of file size and specific image formats. This gives an agent useful constraints without contradicting the annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

A single sentence carries the action, scope, validation criteria, and side-effect exclusions with no filler. All key information is front-loaded and every clause earns its place.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

The output schema covers return-value expectations, and annotations cover safety and idempotency. The description completes the picture with path scoping, format restrictions, and explicit no-network/no-modification guarantees. It is concise but sufficient for a simple validation tool.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 0%, so the description must compensate. It does map the path parameter to a current-working-directory relative path and implies maxBytes through file-size validation, but it does not explicitly name the parameters or explain defaults and bounds. This is adequate but not fully explicit.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description names a specific action (读取/校验) and resource (local image file), and further scopes it to relative paths in the current working directory plus specific formats (PNG, JPEG, GIF, WebP). It clearly distinguishes itself from siblings like generate_image and download_image, which create or fetch images rather than validating existing local files.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description gives clear context for when to use the tool: local files, relative paths, and explicit statements that it does not access the network or modify files. However, it does not explicitly name sibling alternatives or state when to prefer those instead, so the usage guidance is clear but not fully exclusionary.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.