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

Annotations only provide destructiveHint=true, so the description adds real value: it discloses the side effect ('Checkfront adds a note under the acting account') and the eligibility precondition excluding VOID/cancelled bookings. That is meaningful behavioral context beyond the annotation, though reversibility and failure behavior are not described.

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?

Three short sentences, front-loaded with the core action and followed by side effect, constraint, and endpoint. Every sentence carries information. The raw 'POST /api/3.0/...' sentence is mild implementation detail an agent rarely needs, keeping it from a 5.

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 two-parameter mutation with a fully covered schema and no output schema, the description covers the action, the side effect, and the eligibility rules, which is close to sufficient. It stops short of naming the sibling alternative and does not clarify what a successful check-in changes beyond the note.

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%, so the schema already documents both parameters including the checkin/checkout enum, giving a baseline of 3. The description restates the two modes in prose but adds no format or edge-case detail beyond what the schema provides.

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 action on a specific resource: 'Mark a guest as arrived (check in) or departed (check out).' The parenthetical maps the verb to the domain names for both modes, so an agent understands the tool immediately. It does not name its closest sibling (update_booking_status) to differentiate the two, keeping it at 4 rather than 5.

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?

Usage is implied by the description but never stated as a when-to-use rule, and no alternative is named despite checkfront_update_booking_status covering similar territory. The constraint that 'VOID and cancelled bookings cannot be checked in or out' is a genuinely useful precondition that partially compensates.

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