Get author image

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

With no annotations, the description carries the full burden. It discloses that the response is an image (not text) and that it errors if the author has no image. This covers the main behavioral traits beyond the schema, though it omits details like authentication or response format specifics.

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 sentences long, front-loaded with the core purpose and output type, followed by usage and error details. Every sentence adds value, with no redundant or filler content.

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?

Despite having no output schema, the description explicitly states that the return is an image (not text), which is the key contextual information. It also covers the error case (author has no image). For a simple two-parameter tool, this is complete.

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 coverage is 100% with clear descriptions for both parameters, so the description adds little new information. It rephrases the enum values ('thumbnail' = small, 'full' = full-size photo) but does not significantly enhance the semantic meaning beyond what the schema already provides.

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 retrieves an author's photo bytes, with a specific verb ('Get') and resource ('author image'). It distinguishes itself from sibling tools like get_author and get_author_books by focusing on the image. The phrase 'returned as an image, not text' further clarifies the output type.

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?

Provides explicit guidance on using the 'size' parameter ('Use size 'thumbnail' for a small image or 'full' for the full-size photo'). It does not mention alternatives, but the tool's unique purpose (author images) makes it clear when to use it. The instruction 'from list_authors' for authorId also helps context.

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