messages_list_pins

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is clear. The description adds value by specifying the exact return structure (`{pins:[...], count, channel_id}`) and clarifying that structured pin fields are raw Discord data while the human-readable MCP content response fences message text. This goes beyond the annotations, though it does not mention potential permission requirements or edge cases like empty pins.

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 well-structured with bolded headers (Purpose, When to use, When NOT to use, Returns) and concise bullets. It front-loads the purpose, uses short sentences, and contains no fluff; every sentence contributes distinct information.

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 simple read-only tool with one parameter, the description covers purpose, usage context, return format, and a nuance about raw vs human-readable content. Combined with strong annotations and the schema covering all parameters, it provides a complete picture for an AI agent to select and invoke the tool correctly.

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?

The input schema covers 100% of the single parameter (`channel_id`) with a clear description ('Channel to inspect'). The tool description does not add parameter-specific semantics, but the schema already provides sufficient meaning, so a baseline of 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 'List the pinned messages in a channel' with a specific verb and resource, and it distinguishes itself from `messages_read` by explicitly saying 'Reading recent activity → use `messages_read`'. This makes the purpose unambiguous and clearly differentiates from sibling tools.

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?

It includes a dedicated 'When to use' section with concrete use cases ('persistent pinned content (FAQs, rules, announcements)') and a 'When NOT to use' section that names `messages_read` as the alternative. This gives explicit, actionable guidance for when to select this tool over others.

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