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

Annotations already declare readOnly, idempotent, non-destructive behavior, so the safety profile is covered. The description adds valuable beyond-schema context: ordering ('oldest first'), visibility filtering ('Pins of messages you cannot read (history from_join) are left out'), and a trust warning about untrusted text.

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 sentences, front-loaded with the purpose and ordering, then exclusions, then security context. No filler or repetition.

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 structure need not be explained. The description covers ordering, visibility rules, and untrusted-content handling, and annotations cover safety, leaving nothing essential missing for correct invocation.

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%, and both parameters (room_id, agent_id) are fully documented in the schema. The description does not add syntax or usage detail for parameters, so the schema carries the burden and 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?

The description states a specific verb and resource ('List a room's pins') and then defines exactly what a pin is (a message or a task, with its note and pinner). This distinguishes it from siblings like city_room_read or city_room_task_list by scoping to pinned items.

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 implies usage (reading a room's pins) and notes a filtering behavior, but does not say when to prefer this over alternatives such as city_room_search or city_room_read, nor when not to use it.

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