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

Annotations already declare readOnly, idempotent, non-destructive and openWorld, so the safety profile is covered. The description adds the Hamming-distance matching semantics, but no auth, rate-limit, or cost context, and lists return fields that the existing output schema already covers.

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?

A single dense sentence that front-loads the match constraint before the return fields. Nothing is wasted, though it crams parameters, defaults, and outputs into one clause-heavy line.

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 an output schema and rich annotations, the description only needs to add parameter meaning and matching behavior, which it largely does. The undocumented 'limit' parameter and lack of guidance on where to obtain a valid hash_value are minor residual gaps.

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 0%, so the description must compensate. It explains max_distance as a Hamming distance with default 3, hash_type default phash, and that hash_value is an integer perceptual hash — covering three of four parameters meaningfully. Only 'limit' is left undocumented.

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 (Find) and resource (screenshots) and adds scope: matches within max_distance of a perceptual hash. It is distinguishable from search_by_screenshot_hash by the 'similar/distance' framing, though it does not name that sibling explicitly.

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 use case (fuzzy perceptual-hash matching) is implied through max_distance and hash_type, but there is no explicit when-to-use guidance or reference to alternative tools like search_by_screenshot_hash or search_by_fuzzy_hash. Usage must be inferred.

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