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

Discloses behavior beyond the annotations: the raw key is returned exactly ONCE, the minted credential has the same access as the caller's key with no privilege change, and a harness retired in this workspace is refused. This is consistent with idempotentHint=false and destructiveHint=false without restating them.

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?

Front-loads the core action and hierarchy, then layers rationale and constraints. Slightly long and repeats the 'no privilege change' idea twice, but nearly every sentence carries operational weight.

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?

Covers what annotations and schema cannot: credential lifetime (returned once), refusal cases (retired harness, unplaceable name), authorization scope (workspace keys only), and the caller's caching pattern. No output schema exists, and the return-value behavior is explained anyway.

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 schema already documents the harness id format and the refusal-on-unplaceable-name rule in detail. The description's only addition is provenance — the id comes from the initialize handshake — so the baseline of 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 and resource ('Mint the API key for ONE TOOL in this workspace') and precisely places it in a three-tier key hierarchy, distinguishing it from mint_session_key and the folder's workspace key. An agent can tell immediately what it creates and at which level.

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?

Names the caller and the moment of use explicitly: 'The watchdog proxy calls this once it knows which harness is on the other end (the initialize handshake names it)'. It also gives the constraint 'Workspace keys only' and explains the alternative design cost (shared .mcp.json blocking independent retirement) that justifies using this instead.

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