clear_api_key

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

Beyond the annotations, the description adds the significant detail that removal occurs in the OS keychain and leaves the env var untouched. This is meaningful context for a mutating operation, though it does not describe edge cases such as removing a non-existent key; the idempotentHint covers the repeat-safety aspect.

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?

One sentence immediately states the action, target, and scope. Every phrase earns its place, and the parenthetical about the env var is compact but valuable.

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 parameterless tool with an output schema and annotations already present, the description is complete. It tells the agent what will be changed, where, and what will not be affected, leaving no missing information needed to invoke it correctly.

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?

The tool takes no parameters, so schema coverage is trivially 100% and there is no parameter behavior to describe. The baseline of 4 applies because no parameter semantics are needed.

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 uses a specific verb ('remove') and names the exact resource ('stored YNAB API key from the OS keychain'). It also clarifies that the env var is unaffected, which distinguishes it from related credential tools like set_api_key.

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?

Clear scope is provided: only the keychain-stored key is targeted, and the env var remains intact, which implies when to use this tool versus env-var-based configuration. It does not explicitly name alternatives or exclusion conditions, but the context is sufficient for a zero-parameter tool.

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