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

The annotations already declare readOnlyHint, idempotentHint, and non-destructive behavior, so the description faces a lower burden. It does add the explicit 'paginated' behavior, which is useful, but it omits details like default limits, maximum pages, or how similarity_threshold affects results. This is adequate but not rich.

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 a single, front-loaded sentence with no filler. The parenthetical 'paginated' adds functional value, but the overall structure is minimal and does not attempt to organize the multiple parameters or usage context.

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 an output schema, the tool is under-described for correct invocation: hash parameters are ambiguous, similarity_threshold is unexplained, and no sibling differentiation is provided. The description conveys only the basic resource and pagination, leaving significant gaps for an agent deciding whether and how to call it.

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%, yet the description provides no explanation of hash_type formats, hash_value encoding, similarity_threshold semantics, or how page and limit behave. With zero parameter documentation in both schema and description, the agent is left to guess the meaning of every input beyond raw names and types.

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 states a concrete action ('Search scans') and a specific resource ('by screenshot hash'), with a notable pagination detail. It is clear and actionable, though it does not explicitly differentiate itself from overlapping siblings like search_similar_screenshots.

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?

No guidance is given on when to choose this tool over alternatives such as search_similar_screenshots, search_by_fuzzy_hash, or search_by_favicon. The agent must infer usage solely from the tool's name and generic description, which is insufficient given the large sibling set.

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