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

Annotations already declare mutation, idempotency, and non-destructiveness; the description adds meaningful context beyond them, including 'Free and instant', the prerequisite original photo, and the fact that generated variations remain available and the action is reversible. The word 'discarding' does not contradict destructiveHint=false because the description immediately qualifies it as reversible.

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 description is front-loaded with the action, then adds cost, eligibility, reversibility, and account handling in four tight sentences. Every sentence earns its place and no important information is buried.

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 two-parameter mutation with annotations and an output schema, the description covers purpose, preconditions, side effects, reversibility, cost, and account disambiguation. Nothing an agent needs in order to call it correctly appears to be 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 an account-selection rule beyond the schema: if the user did not specify an account and list_accounts returns multiple, ask rather than choosing for them. It does not add further format semantics for postId, which the schema already documents.

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 states a specific verb and resource: putting a Pin back to its original photo and discarding the generated design. It distinguishes the operation from design generation by naming get_pin_design for eligibility checks and select_pin_design_variation for reversal, so an agent can identify the tool without opening 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?

It gives an explicit precondition: only works when get_pin_design lists 'revert' in supportedOperations and the Pin still carries its original photo. It also names select_pin_design_variation as the reversible alternative and instructs the agent to ask the user when multiple accounts exist, which is unusually specific routing guidance.

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