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

Annotations only indicate readOnly and openWorld, but the description adds substantial behavioral context: it prices and scores the exact contract, returns live quote, Greeks, premium, collateral, yield, expiration probability from the seller's side, and RENT score. It also explicitly says that if pricing fails it will say so and why, rather than substituting another contract, and that the output is analysis, not a recommendation.

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 dense but well-structured: purpose first, then differentiation, then return contents, then failure behavior, then a caveat. Every sentence adds distinct value and there is no filler or repetition of schema fields.

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 tool with no output schema and only 29% schema description coverage, the description is unusually complete. It covers what the tool returns, how it behaves on failure, and how to interpret the output (analysis, not a trade recommendation). The only minor omission is context for lang/risk, but their enum values are mostly self-explanatory.

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 only 29%, so the description carries real weight. It correctly maps the four required parameters to a concrete contract and adds meaning for strike ('including strikes the screener would never surface'). However, it does not describe the optional lang and risk parameters, leaving their semantics to the schema's enum values.

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 opens with a specific verb and resource: 'Explain ONE specific option contract the user named' and enumerates the contract components (ticker, put/call, strike, expiry). It also explicitly contrasts with explain_score and compare_candidates, so an agent can immediately tell this tool apart from alternatives.

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 clearly states when to use this tool: when the user names an exact contract, including strikes the screener would not surface. It names the alternatives and explains their limitation ('can only explain contracts the engine already picked'), which gives the agent a concrete routing rule.

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