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

Annotations already declare write (readOnlyHint=false), non-idempotent, non-destructive. The description adds important context beyond those flags: the created token is shown once and cannot be read again, the returned plaintext_token must be stored, and a get_key-issued key cannot mint further keys. It does not fully detail what happens with the monthly cap when omitted, but the schema already covers that.

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 dense but effective: three well-organized sections (purpose, exclusions, return contract). It front-loads the purpose and immediately names alternatives. The only minor inefficiency is repeating 'Creates a key' at the end after already saying 'Create an additional API key', and the return-value list could be considered somewhat long, but each clause earns its place given there is no output schema.

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 2-param tool with no output schema, the description covers the full call contract: what it returns (including that plaintext_token is shown once), when to use, when not to use, and the alias/constraint. The only minor gap is it doesn't state the exact auth mechanism beyond 'Needs your API key', but that matches the tool family and the given context signals; the description is complete enough for correct invocation.

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 description coverage is 100%, so the schema documents both parameters. The description adds context for monthly_request_cap ('own budget', 'fleet spend control') which reinforces the schema's wording, but doesn't add new meaning beyond it. The 'not: type: null' schema oddity for monthly_request_cap is a schema detail, not something the description needs to compensate for. Baseline 3 is appropriate.

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?

States a specific verb+resource ('Create an additional API key'), and explicitly distinguishes itself from siblings: 'Not for your first key (use get_key, no signup) and not for a wallet-proven agent key (use claim_agent_start)'. An agent can tell it apart from get_key, list_api_keys, revoke_api_key, and configure_key without opening schemas.

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?

Explicitly says when to use (give a service or teammate its own key/budget) and when not to (first key → get_key, wallet-proven agent key → claim_agent_start). States a prerequisite ('Needs your API key') and a hard constraint ('a key obtained from get_key cannot mint further keys'). No exclusions are left to inference.

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