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

Annotations already declare readOnlyHint=false, destructiveHint=false, idempotentHint=false, and openWorldHint=false, so the safety profile is largely covered. The description still adds genuine value: the secret is returned only once and each call mints an additional key (up to 20 active per user), which explains the non-idempotency in practical terms. Missing: nothing about secret lifetime, revocation of the new key, or error behavior when the 20-key ceiling is hit.

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 core action and its one-time-secret return, then the permission and quota rules. Every clause carries information; nothing is redundant with the title or 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 three-parameter credential-minting tool with full schema coverage and an output schema, the description covers the dimensions that matter: what is produced, that the secret is unrepeatable, who may grant which scopes, and the per-user key cap. No material gap remains.

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 a baseline of 3 applies, but the description goes beyond the schema by constraining what can go into scopes (readers restricted to read, owner-only billing:write, delegated keys capped at their own breadth). That is real semantic guidance the enum-free scopes array does not convey on its own.

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 concrete verb+resource pair (creates an API key) plus scope of effect (for yourself, in this agency, limited to requested scopes). No sibling tool in the list issues credentials, so the operation is unambiguous without needing an explicit contrast.

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?

Gives the operative preconditions for use: readers cannot request write scopes, only the agency owner may request billing:write, and a delegated key cannot mint a broader key than itself. It stops short of naming an alternative tool or stating when not to use it, but within this context there is no obvious substitute.

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