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

With no annotations, the description must disclose behavioral traits. It states that the operation signs up the calling user, but it does not explain the effect (e.g., creating a registration, sending notifications), idempotency, failure modes, or any preconditions like whether the signup must be open. For a mutation tool, this is a significant gap.

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?

The description is three concise sentences, front-loaded with the core purpose, then the parameter simplification, and finally the usage alternative. No redundant words, and it flows efficiently.

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?

The tool has 4 parameters including a nested selections array, no output schema, and no annotations. The description does not cover parameter semantics, behavior, or return values. While it differentiates from register_participant, it lacks essential details for an agent to call it correctly, such as what selections represents or how custom fields work.

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 only 25%, and the description does not explain the required parameters signupId or selections. It only mentions that name/email come from the account, which is not about parameters. The description fails to compensate for the low schema coverage, leaving the agent without meaning for the core inputs.

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 clearly states the tool's purpose: to sign up the calling user (self), explicitly noting it is not for registering others. It distinguishes itself from register_participant by name and scope, so an agent can immediately tell what it does and why it differs.

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 explicitly says to use this for self-service flows and to use register_participant for registering someone else. It also clarifies that name and email come from the user's account, which removes the need to provide participant input. This gives clear when-to-use and when-not-to-use guidance with an alternative.

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