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

Annotations already cover read-only, idempotent and non-destructive semantics, so the bar is lower; the description adds real value by naming the return fields (id, provider, preview_url, size, photographer) that an agent needs to present results. It doesn't discuss rate limits, result counts, or what happens when the provider returns nothing.

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?

Three sentences, front-loaded with purpose, then return shape, then the downstream call, then a query tip. No filler and nothing requires re-reading.

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?

With no output schema, the description usefully substitutes by enumerating returned fields and the handoff contract. The minor gap is pagination: the page parameter and how to get further results are not mentioned anywhere.

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 already 80%, yet the description still adds meaning: it establishes the query→add_stock_photo(provider, id) linkage across parameters and gives a concrete query example. The only undocumented parameter is page, which is bounded in the schema.

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?

States a specific verb and resource ("Search free stock photos") plus the two providers, and immediately frames the outcome ("to illustrate a post"). It separates itself from sibling tools like add_stock_photo and generate_image by naming its role as the discovery step.

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?

Gives an explicit next step: "Use add_stock_photo with the chosen provider and id to put it in the Media Library ... and get a media_uid for create_post." It also gives query-shaping advice ("Short, visual queries work best"). It stops short of saying when not to use this (e.g. vs generate_image or add_media_from_url for non-stock sources).

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