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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint, so the safety profile is covered. The description adds genuinely new context: that the call is free, that it returns ids rather than content, and that it will not perform payment or return live prices. It does not cover pagination or result limits, which keeps it out of the top band.

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?

Two sentences, zero filler, front-loaded with the action and resource before the caveats. Both the return shape and the exclusion are stated in the fewest possible 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?

With an output schema present, return formatting needn't be described, and annotations carry the safety profile; the description still usefully names the id-based return contract and the payment/price exclusions. What is missing is any hint about result volume or how to page/refine, which a search tool would benefit from.

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?

There is a single parameter with 100% schema description coverage, and the schema already supplies constraints (1-120 chars) and example queries. The description adds only the word 'keyword', which conveys little beyond the schema's own examples, so this sits at the schema-driven baseline.

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 (search) and resource (Blocksize documentation and catalog metadata) with the scope qualifier 'by keyword'. It also draws a boundary around what it returns ('document and instrument ids for fetch') and what it does not ('live prices'), which lets an agent separate it from get_pricing_info and get_market_data_endpoint.

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 says the results are ids 'for fetch', effectively routing the agent to the fetch sibling as the next step, and rules out live-price/payment use cases. It stops short of naming the alternative tools explicitly (e.g. use get_pricing_info for prices), so the when-not guidance is implied rather than spelled out.

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