Get author photo URL

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

Annotations declare readOnlyHint=true and openWorldHint=true, indicating safe read and possible missing data. The description adds that it reports when no photo exists, which aligns with openWorldHint and provides meaningful behavioral context beyond the annotations. This handles the missing photo case explicitly, which is valuable for agents.

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 function ('Get the URL'), and each sentence provides essential detail (ID format and missing-photo behavior). No wasted words.

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?

Given the tool's simplicity (single param, no output schema), the description is highly complete. It covers the purpose, the ID, and the edge case of missing photosabbia. While it doesn't mention return format, the lack of output schema means it's not required, and annotations cover safety aspects.

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 coverage is 100% and the schema already describes the olid parameter. The description's example (OL23919A) reinforces the format and makes it clearer for agents, adding value beyond the schema. This is effectively a baseline 3 with a bonus for the example, and given the high coverage, it's sufficient.

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 it gets the URL for an author's photo, specifying the resource (author's photo) and the required identifier (OLID), and even includes an example. It distinguishes itself from siblings like get_author_info and get_book_cover by focusing specifically on photo URLs and handling missing photos.

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 when to use this tool (when needing an author's photo URL) and provides guidance on the ID format, but it does not explicitly state when not to use it or mention alternatives. Since there are sibling tools like get_author_info that might also provide photo info, explicit exclusions would help, but the context is clear enough.

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