connect_account

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

Annotations already declare a non-read-only, non-destructive, open-world operation, so the mutation profile is covered. The description adds that the call returns library cards, but says nothing about failure modes for an invalid/expired code, idempotency, or what re-linking does to existing state.

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 sentences, front-loaded with the action and with a useful note on the return value. The return-value sentence is slightly redundant given an output schema exists, but it costs little.

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?

A single-parameter tool with full schema coverage, an output schema, and annotations needs little more from the description. What is missing is mild: behavior on an invalid code and whether the call can be re-run safely.

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% and the sole parameter is fully documented in the schema, including its provenance ("Libby's 'Copy To Another Device'"). The description adds no semantics beyond that, so the baseline 3 applies.

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?

A specific verb and resource ("Link the user's Libby account") plus a statement of what comes back ("linked library cards"). It is distinguishable from get_account, which reads existing account data, but the description never names a sibling, so differentiation is by inference.

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?

"one-time setup code" implies this is a first-time onboarding step rather than a repeatable operation, which is useful context. However, there is no explicit guidance on when to call this instead of get_account, or what to do if the account is already linked.

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