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

Annotations already cover read-only, idempotent, and non-destructive behavior. The description adds valuable context beyond annotations, including the $0.001 USDC per-call cost and the fact that the response is byte-identical to a specific REST endpoint.

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 three short sentences, each earning its place: the core data content, the cost warning, and the exact endpoint equivalence. It is front-loaded with the most important identifying information and contains no filler.

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?

For a simple read-only tape tool with an output schema and fully documented parameters, the description is nearly complete. It covers cost, data fields, and endpoint identity; the only minor gap is explicit guidance on when to choose this over sibling trade tools.

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 100%, so the parameters are already well-documented in the schema. The description's example endpoint reinforces the parameter values but does not add substantial new meaning beyond what the schema provides.

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 identifies the tool as a fill-by-fill trade tape from OKX and lists the key fields returned: aggressor side, price, size, and venue timestamp. It distinguishes itself from sibling exchange trade tools by naming OKX and the specific endpoint, though it lacks an explicit verb like 'returns'.

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 usage for retrieving recent OKX trade fills, and the cost warning provides a practical consideration. However, it does not explicitly state when to prefer this tool over alternatives such as market_okx_candles or other exchange trade tools.

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