registry_create_api_key

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

Adds real state facts beyond the annotations: the key is shown once and must be stored, max 3 active keys per wallet, and requests past the daily cap fall back to x402. That is substantive operational context. The closing sentence ("writes state upstream (not read-only)") largely restates readOnlyHint=false rather than adding new information.

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-loaded with purpose and the one-time-return warning; the sibling exclusion follows immediately. The trailing "Behavior:" sentence is boilerplate that partly duplicates the annotations and could be dropped without loss.

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?

No output schema exists, and the description compensates by describing the return value ("wr_...") and how to use it as api_key with registry_search_tools / registry_tool_detail. Prerequisites, quota limits, and failure fallback are all covered for a write tool.

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%, so the baseline is 3, but the description adds cross-tool meaning: the signature is over the message obtained from registry_onboarding_message(action=api_key) and the timestamp must be the one returned with that message. That is more than the schema's one-line parameter docs convey; the optional label parameter is left unaddressed in the description (schema covers it).

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?

Names a specific verb+resource (create API key), states its position in a workflow ("Step 2 of getting a free API key"), and explicitly excludes the adjacent use case ("Not for inspecting a key (use registry_key_info)"). An agent can place it against registry_key_info / registry_onboarding_message without opening any schema.

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 an explicit precondition ("Use when you signed the onboarding message") plus the goal ("want a free Registry API key"), names the sibling that produces the prerequisite message (registry_onboarding_message(action=api_key)), and routes the look-up case to registry_key_info.

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