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

With no annotations, the description carries the full behavioral burden and does so well: the key is displayed once (irreversible if lost), valid 90 days, and silently invalidates any existing key — an important destructive consequence an agent must know before calling. It also gives the exact header format for subsequent use.

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?

Three sentences, zero filler, front-loaded with the purpose before the lifecycle caveats and the header usage note. Every sentence adds information an agent needs.

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 tool with no output schema or annotations, the description covers the outcome, key lifetime, replacement semantics, and usage format. It does not say what happens on an invalid or expired code (error shape), a minor remaining gap.

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% with only two well-documented parameters, so the baseline is 3; the description adds the useful fact that the code arrives by email and is bound to the address, which clarifies the coupling between the two parameters beyond the schema's individual field descriptions.

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?

'Trade the emailed code for your API key' states a specific verb (exchange) and the actual resource produced (API key), which is more precise than the tool name verify_agent_email would suggest. It is clearly distinguishable from create_agent_account and revoke_api_key, which bracket it in the account lifecycle.

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?

'The emailed code' implies this runs after a code is issued (i.e., after create_agent_account) and the replacement note implies it is not for rotation-free reuse, but the description never states prerequisites or explicitly contrasts with revoke_api_key. Usage is inferable rather than stated.

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