Get a Pin

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

Annotations already establish read-only, idempotent, non-destructive, open-world behavior, so the bar is lower, yet the description still adds meaningful context: a dated permission gate (PINNER_DATA_ACCESS_DENIED for apps registered on or after 14 September 2026) plus an explicit instruction not to retry. That is exactly the kind of failure-mode guidance annotations cannot express. It does not describe pagination or rate-limit behavior, which is minor here.

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?

Two tight sentences with no filler: the first front-loads what is returned, the second front-loads the parameter rule and then the error contingency. Nothing repeats the tool name or title, and no sentence could be dropped without losing 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?

With an output schema present, the field list is technically redundant, but it usefully previews shape without cost. The two-parameter surface is fully accounted for and the notable failure mode is documented. The only gap is sibling disambiguation, which matters given a crowded pin-related toolset.

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 0%, and both parameters are bare strings in the schema, so the description carries the burden. It explains the conditional, optional nature of ad_account_id (only when the Pin belongs to that ad account's profile), which the schema does not convey at all. pin_id is left as self-evident; it could have noted where a pin_id is obtained.

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 and resource ("Get one Pin") and enumerates what comes back (title, link, media, board, promoted status), which is far more informative than the name alone. It never names the nearby siblings (list_pins, list_board_pins), so an agent must infer that this is the single-record fetch rather than a listing call.

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 gives a concrete conditional rule for ad_account_id ("Pass ad_account_id when the Pin belongs to that ad account's profile") and a clear do-not-retry directive for the 403 case, which is real usage guidance. It stops short of saying when to choose this over list_pins or list_board_pins, or what to do if the pin_id is unknown.

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