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

No annotations are provided, so the description carries the full burden, and it does well: it discloses the human-approval step (an email link), the asynchronous nature (poll), and the token-collection outcome. It doesn't cover failure modes, expiry of the signup request, or rate limits, but it is unusually rich for a create tool.

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 tight sentences, zero waste, with the primary action front-loaded and the required follow-up second. Every clause earns its place.

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 3-param create tool with no output schema and no annotations, the description supplies the lifecycle the agent needs: email approval, signup_id, polling, token. It could say more about what the initial call returns or approval timeouts, but it is largely sufficient.

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% (agent, email, project all documented inline), so the baseline is 3. The description adds identity semantics for email ('join theirs if their email already has one') but says nothing about the agent or project params beyond the schema.

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+resource ('Create a Plinth account') and immediately clarifies the dual behavior: create new, or join an existing account if the email already has one. An agent can distinguish this from account.status and other siblings without opening a 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?

Explicitly covers the branch conditions (new vs. existing email) and prescribes the follow-up workflow: 'call account.status with the returned signup_id and poll to collect your token.' It names the sibling and the exact next action, leaving nothing to inference.

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