discord_pin_message

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

Annotations already carry readOnlyHint=false, destructiveHint=false, and idempotentHint=true, and the description meaningfully extends these: it details the auth requirement (dedicated Pin Messages permission, distinct from Manage Messages), the operational limit (50 pins max), and precisely what idempotency means here (pinning an already-pinned or unpinning an unpinned message has no effect). No contradiction with 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?

Three tight sentences (~60 words) with zero filler. The core behavior and controlling flag are front-loaded, followed by permission, limit, and idempotency details in decreasing order of importance. Every sentence earns 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 simple 3-parameter mutation with full schema coverage and strong annotations, the description covers behavior, mode selection, permission prerequisites, capacity limits, and idempotency semantics. No output schema exists, but pin/unpin operations have trivial success responses, so return-value documentation is not a meaningful gap.

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%, so the baseline is 3 even without parameter info in the description. The description's 'controlled by the pin flag' restates the schema's 'true to pin the message, false to unpin it' rather than adding new meaning. The schema also already documents the snowflake patterns and thread support, so the description adds no value beyond it.

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 a specific verb+resource pair ('Pin or unpin a message in a channel') and immediately clarifies the dual-mode behavior via the pin flag. This distinguishes it from siblings like discord_delete_message, discord_send_message, and discord_fetch_pinned_messages without needing to inspect 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?

Gives clear operational context: the Pin Messages permission is a dedicated permission separate from Manage Messages, channels cap at 50 pins, and the operation is idempotent. It does not explicitly name alternatives (e.g., discord_fetch_pinned_messages for reading pins) or state when-not-to-use conditions, but the context is substantial enough to guide correct invocation.

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