image_metadata

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

With no annotations, the description carries the burden of disclosure. It explains that the tool works via HTTP headers and does not download images, but it does not mention potential edge cases like missing headers, redirects, or rate limits. This is adequate for a simple read operation but not comprehensive.

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?

The description is two short, focused sentences. It front-loads the action and enumerates specific metadata types without any redundant or vague wording.

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?

For a tool with only one parameter and no output schema, the description effectively communicates what metadata will be returned and the method used. It lacks edge-case handling details, but is otherwise complete enough for an agent to invoke it correctly.

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?

The schema already fully describes the url parameter as 'Direct URL to an image file' (100% coverage). The description adds context about HTTP headers but does not further clarify the parameter itself, so a baseline 3 is appropriate.

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 clearly states the tool reads image metadata from a URL via HTTP headers, listing specific fields like content-type, file size, and cache info. This definitively distinguishes it from siblings such as find_favicons or generate_placeholder.

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 implies usage for fetching metadata without downloading the image ('No image downloading required'), which gives clear context. However, it does not explicitly mention when not to use it or compare to alternatives, so it falls short of a 5.

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