messages_list_pins

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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive behavior, so the description adds value elsewhere: it explains pagination mechanics and the return-shape details such as 'Structured pin fields remain raw Discord data; the human-readable MCP content response fences message text.' This is meaningful behavioral context beyond the annotations.

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 bold section labels, front-loads purpose, and each sentence carries useful information. It covers purpose, alternatives, pagination, and return format without unnecessary filler.

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 read-only list tool, the description is complete: it covers when to use it, when not to use it, pagination mechanics, and the exact return structure. The annotations handle the safety profile, and the return description covers the output shape, so nothing an agent needs to call this correctly is missing.

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 schema already documents all three parameters with 100% coverage, so the baseline is 3. The description adds semantic value by explaining that 'before' is an ISO 8601 timestamp from a prior pinned_at and that 'next_before' is the last item's pinned_at for the next page — details not present in the schema descriptions.

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 opens with 'List the pinned messages in a channel' — a specific verb and resource that immediately identifies the tool's function. It also differentiates from the sibling messages_read by explicitly stating that reading recent activity should use that alternative.

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 provides explicit 'When to use' and 'When NOT to use' sections, including a named alternative ('use messages_read' for recent activity). Pagination usage is also specified with concrete fields ('before', 'limit', 'has_more', 'next_before'), leaving no ambiguity about how to page through results.

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