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

With no annotations, the description carries the full burden and does disclose the permission model, the duration default (permanent when null/omitted), and a precondition. It stops short of stating idempotency (pinning an already-pinned post) or how the pin is later removed.

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 short sentences, no filler, with the action and permission scope front-loaded before the constraint clauses.

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?

No annotations and no output schema, so the description must stand alone; it covers authorization, duration, and preconditions well. It leaves minor gaps around re-pinning behavior and the unpin path, but nothing that would cause a misinvocation.

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 coverage is 67%; days is already documented in the schema including its null semantics, and boardSlug is described there too. The description restates the days range and permanence rather than adding new meaning, and says nothing about postId.

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?

States a specific verb and resource ('Pin a post to the top of a board') and immediately qualifies the operation with an authorization scope. An agent can distinguish it from mod_unpin_post and admin_set_pin without opening any 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 the authorization model ('any moderator of that board; admins unrestricted') and a hard precondition ('the post must already belong to the board'). It does not name the inverse sibling mod_unpin_post or explain when admin_set_pin should be preferred, so the alternative-routing is left implicit.

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