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

Annotations only flag non-read-only, non-idempotent, non-destructive; the description goes well beyond that by disclosing that the action is Tailwind-local and changes nothing on Pinterest, is free (no Pin credits), and that duplicate calls create duplicate lists. The retry guidance and the 20-board interval-pinning limit are exactly the behavioral context annotations cannot carry.

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?

Front-loaded with the trigger condition, then progressively adds cost, ordering, return value, idempotency, and account selection — a sensible priority order. It is on the long side and the "it is free — it does not consume Pin credits" clause is slightly redundant, but no sentence is 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 3-parameter write tool with an output schema, nothing material is missing: the data source for boardId, ordering semantics, cost, side-effect scope, duplicate-call risk, retry path, and account ambiguity are all addressed, so an agent can call it correctly without further inference.

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 already 100%, so the baseline is 3; the description adds meaning by specifying that boards must be supplied in publishing order and that boardId values come from list_boards or a just-created create_board, plus noting the returned boardListId. It stops short of covering name constraints or the per-board section option, which the schema already handles.

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?

Opens with a specific verb and resource ("create a saved board list") and immediately defines the resource: "a named, ordered grouping of their boards." It also ties the object to a downstream use (create_post's intervalBoards), which distinguishes it cleanly from siblings like update_board_list, list_board_lists, and delete_board_list.

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 an explicit trigger ("Use this when the user wants a saved board list"), names the alternative for the ambiguous-retry case (check list_board_lists before retrying), and routes account disambiguation to list_accounts with instructions to ask the user rather than choose. Exclusions and prerequisites are both present.

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