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

Annotations already declare destructiveHint=true, idempotentHint=true, and readOnlyHint=false, so safety is covered. The description adds genuinely useful boundary context: 'This never edits the shared city catalog record,' scoping the blast radius of the destructive operation. It stops short of saying whether the old association is recoverable or what the response returns.

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?

Two short sentences, zero waste. The primary action is front-loaded and the boundary clarification follows immediately, each earning 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 5-param mutation tool with full schema coverage and annotations covering the safety profile (destructive/idempotent/not-read-only), the description is nearly complete. Only a note on reversibility or confirmation of the replaced association would make it fully sufficient; no output schema exists, so return values are rightly not explained.

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 each parameter carries a detailed description, including the city_id/city_name OR-relationship and the country disambiguation hint. The description text adds no parameter-level meaning beyond this, so the 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: 'Replace one trip-city association with another city.' This semantically distinguishes it from the add/remove/reorder siblings, though it does not name any of them explicitly. An agent can tell what it does 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?

The 'replace' framing implies when the tool applies (an existing association needs to change city), but there is no explicit when-to-use guidance, no mention of trip_city_add vs trip_city_remove as alternatives, and no prerequisites. Usage is left to inference.

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