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

Annotations declare destructiveHint=true and idempotentHint=false; the description adds genuinely non-obvious context: no notification is sent, the action is reversible in one call, and it executes without confirmation. That is useful beyond the structured flags, though it leaves the destructiveHint tension (a 'destructive' mutation framed as harmless) unaddressed.

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 opening sentence and the following sentence restate the same information nearly verbatim ('Pin a post to the top of the feed (up to 3) or to a Classroom page (up to 12)' vs the longer rewording). Roughly a third of the text is redundant padding.

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?

With four params, no output schema, and annotations carrying the safety profile, the description covers permissions, both targets, caps, the unpin path, and reversibility — enough to call correctly. Only edge-case behavior at capacity 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?

Schema coverage is 100%, so the baseline is 3; the description adds value by tying course_page_id to the Classroom target and the 12-post cap versus the 3-post feed cap, making the two pin targets semantically distinct. It doesn't clarify what happens when both limits are hit, which is the main remaining ambiguity.

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 (pin) and resource (post), plus the two distinct targets (feed vs Classroom page) and their respective caps (3 and 12). An agent can immediately distinguish this from pin_comment or update_post.

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 explicit eligibility (admins only) and the condition for the inverse operation ('Set pinned to false to unpin'). It does not name a sibling alternative or state when not to pin, but the usage context is clear enough to act on.

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