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

Annotations are all false, providing no safety hints. The description adds meaningful behavioral context: it creates an account (state-changing), claims guest links, and importantly warns that 'Long-lived API keys are never returned over MCP,' which is a security-relevant disclosure beyond the annotations.

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, each earning its place. The first packs the entire flow, and the second adds a critical security caveat. No redundancy or filler.

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 multi-step mutation tool with an output schema present, the description covers the essential sequence (verify, create, claim, continue OAuth) and a key limitation. It does not explicitly spell out the prerequisite of having requested a code, but the flow is inferable from the sibling tools and the wording.

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%, with each parameter (email, code) already described in the schema. The description adds no additional parameter semantics, 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?

The description states a specific verb-resource action: 'Verify the emailed code, create the account, claim guest links, and continue with OAuth 2.1 + PKCE.' It clearly distinguishes from siblings like send_registration_code and create_guest_token by describing the full account creation flow.

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?

The description implies clear usage context: after an email code has been sent, this tool completes the registration. It does not explicitly name alternatives or exclusions, but the context is unambiguous and the sibling list makes the alternative explicit enough.

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