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

Annotations cover the safety profile (readOnlyHint=false, idempotentHint=false). The description adds behavior annotations don't carry: the key is 'shown once,' the call needs no existing credentials, and how the returned credential should be supplied on subsequent calls. It does not mention rate limits or failure modes, so a 4 rather than 5.

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 purpose and the one-time-key caveat before the usage instructions, and the example is concrete rather than filler. The sentence is long and could be split, but every clause carries information.

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?

Despite having no output schema, the description names the return values (api_key, agent_id) and the one-time display constraint, and explains the bootstrap/authentication flow. An agent has everything needed to call it once and use the result.

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 name, contact_email, intended_use, and via are all already documented at the source. The description adds no semantics for these four inputs (its api_key mention belongs to later tools, not this schema), so the baseline 3 applies.

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?

Specific verb+resource (register the agent, obtain its API key) and explicitly identifies itself as the MCP equivalent of a named REST endpoint. No sibling tool competes for this purpose, so disambiguation is inherent.

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?

States 'no key needed' and gives the full follow-up path: either attach the key as an X-API-Key/Bearer header or pass it as the api_key argument on later calls, with a concrete example (get_deposit_address). There is no 'when not to use' because no alternative registration tool exists, but the post-conditions are unusually clear.

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