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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is known. The description adds behavioral detail beyond that: it specifies the scope includes 'everything sent to the guest, automatic mail included', which is non-obvious and valuable. It also confirms consistency with the UI ('The same thread the panel shows'), giving the agent confidence in output relevance. No contradictions with annotations; this is an additive transaction.

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 a single, concise sentence that packs essential details: the scope (one reservation), the inclusion of automatic mail, and the UI consistency. It is front-loaded with the core purpose and has zero filler. Every phrase earns its place.

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 one parameter, a high-coverage schema, existing output schema, and read-only annotations, the description is complete. It tells the agent what the output will contain (all messages sent), the scope, and the relationship to the panel. No missing information that would prevent correct invocation or interpretation.

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% (reservation_id is described with a clear source: 'from list_reservations'). The tool description does not add any extra parameter semantics beyond the schema. Per the rubric, when schema coverage is high, baseline is 3, and the description does not compensate with additional parameter guidance (e.g., format, constraints). This is adequate but not enhanced.

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 states the verb (list is implied by 'Message history') and the specific resource: messages for one reservation. It distinguishes itself from siblings by specifying it covers 'everything sent to the guest, automatic mail included', which is specific to this tool and not described in list_reservations or get_reservation. The phrase 'The same thread the panel shows' further anchors its distinct scope.

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 gives clear context: it is for a single reservation ('for one reservation') and is for message history. However, it does not explicitly mention when not to use it or name alternative tools (e.g., get_reservation for details, list_reservations for reservation summaries). It implies usage based on the need for message history, but lacks explicit exclusions or alternative routing.

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