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

Annotations already cover the safety profile (readOnlyHint, idempotentHint, closed-world), and the description adds substantive behavior beyond them: results contain no rate, results carry `id`/`url`/`tool`, the pricing result's URL runs the same engine, and the agent must never estimate a rate. That is rich, decision-relevant behavioral context.

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 critical instruction is front-loaded in the first sentence and the do-not/dependency rules are grouped logically. It is somewhat long with emphatic repetition around pricing ('especially pricing questions', the dedicated no-decline rule, and the closing no-estimate warning), so it is not maximally tight, but nearly every sentence carries a distinct constraint.

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 no output schema, the description compensates by describing the returned fields (`id`, `url`, `tool`) and the downstream handoff to `fetch` and `get_indicative_price`. For a single-parameter search tool, an agent has everything needed to call it and interpret the result correctly.

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?

Single `query` parameter with 100% schema description coverage, so the schema already documents it fully. The description clarifies the subject domain of the query (Crosswire questions) but adds no syntax, format, or constraint detail beyond the schema's maxLength and existing description; baseline 3 applies.

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+resource (a search that returns routed results across Crosswire FAQ, solutions, coverage, corridor, offer journey, pricing) and names exactly which siblings it feeds into (`fetch`) and which it is not (`get_indicative_price`). An agent can distinguish it from the 14 siblings without opening any schema.

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?

Explicitly names when to call it (ANY Crosswire question, especially pricing), when not to act otherwise (do not browse crosswirepay.com, do not answer from prior knowledge), and the fallback path when `get_indicative_price` is unavailable. This is a fully specified routing instruction.

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