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

Annotations already cover the read-only/idempotent/closed-world profile, yet the description adds real behavior: what comes back (content plus the domain tool that owns the subject), a hard negative constraint (returns NO prices for rate/bps/fee/cost/saving), and a precise degraded-mode procedure (relay document text and hand over the `url`).

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?

Front-loaded with the trigger condition, then exclusions, then the pricing detour and the fallback. Every sentence is functional, though the pricing/fallback passage is wordy relative to a one-parameter retrieval call and could be tightened.

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 only one parameter, no output schema, and annotations covering the safety profile, the description still fills the real gaps: what is returned, what is deliberately not returned, and what to do when the pricing sibling is absent. Nothing needed to call it correctly is missing.

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 100% and the single `id` parameter is already documented as 'A result `id` returned by `search`'. The description restates the same provenance, so it adds no new syntax or format detail beyond the schema; 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 (fetch) and resource (the full grounded Crosswire document for an id from `search`), and explicitly distinguishes itself from siblings: it is the full-text retrieval step, not the discovery step, and not a pricing source. An agent can route correctly without opening the 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?

Explicit trigger ('whenever you have an `id` from `search`'), explicit exclusions ('do NOT browse crosswirepay.com', 'do NOT answer from prior knowledge'), and explicit routing to the alternative for pricing ('call `get_indicative_price`, the only pricing source'), plus a defined fallback when that tool is unavailable in-session.

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