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

Annotations already declare readOnlyHint, idempotentHint, non-destructive, and closed-world, so safety is covered. The description adds genuinely non-obvious behavior: contact only via `howToContactSeller`, delivery terms limited to `delivery.summary`, and the explicit warning that no price or delivery has been agreed through this tool — valuable anti-hallucination framing. It does not say what happens when a slug is stale or the listing is removed, which is the main remaining gap.

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 resource and returned fields, then the parameter source, then a usage example, then behavioral caveats — a sensible ordering. The final sentence is longer than strictly necessary and packs three distinct constraints together, but each one carries real disambiguation value.

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?

An output schema exists, so return-value documentation is not required, yet the description still orients the agent by naming the main field groups. Combined with the marketplace-vs-seller caveats, it covers everything needed to call correctly. Only the missing note on invalid or delisted slugs keeps it from a 5.

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% with a single required `slug` parameter already documented with an example format, so the baseline is 3. The description adds only the provenance note that the slug comes from a listing result, which is modest added meaning rather than format or validation detail.

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 and resource ("Full details for a specific bike listing on Cyclesite") and enumerates the content returned: specs, condition, frame number presence, photos, delivery, seller's city. This clearly separates it from siblings like search_bikes, get_spec_sheet, or get_model_info, which do not return a single listing's full record.

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?

"Takes the URL slug from a listing result" tells the agent the precondition and where the identifier comes from, and the example utterance ("tell me more about that 2022 Trek Domane") shows the triggering conversational context. It lacks explicit when-not-to-use guidance, e.g. pointing to get_spec_sheet or get_model_info when the user wants model-level rather than listing-level data.

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