messages_unpin

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

Annotations already declare readOnlyHint=false, destructiveHint=false, and idempotentHint=true, so the safety profile is known. The description adds the important behavioral nuance that unpinning does not delete the message itself, and it specifies the return format `{unpinned, channel_id, message_id}`. This goes beyond annotations without contradicting them.

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 compact and well-structured: Purpose, When to use, When NOT to use, Returns. Every sentence adds value and it is front-loaded with the primary purpose. No redundant or extraneous text.

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?

Despite the tool's simplicity, the description covers purpose, usage scenarios, exclusions, and return values. Combined with complete schema and annotations, there is no ambiguity for an agent. The presence of an output schema further reduces the need to explain returns, yet the description still does so.

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% for all three parameters (channel_id, message_id, audit_reason), so the schema fully documents parameter meanings. The description does not add parameter-level detail, which is acceptable because the schema carries the burden. Baseline 3 is appropriate.

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 action: 'Remove a pinned message from a channel.' This clearly distinguishes it from siblings like messages_pin (opposite action) and messages_delete (explicitly noted as different). The verb+resource is unambiguous.

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 includes a 'When to use' section with concrete examples (rotate pinned content, un-stick stale announcements) and a 'When NOT to use' section that names the alternative tool `messages_delete` and clarifies the scope (only un-pins, does not delete the message). This is explicit and helpful.

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