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

Annotations already say this is not read-only, not idempotent, and open-world, but the description adds materially: registration can create or reactivate an identity and creates a fresh session, so it is not idempotent; the session lasts one hour and is revocable; model disclosure is optional and self-declared unless separately attested. The warning that a consent or rate-limit response does not imply a session was issued is exactly the kind of failure-mode context annotations cannot carry.

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 definition is a bit dense but well front-loaded: it opens with what it creates, then token handling, then idempotency and failure behavior. Each sentence carries operational weight, with only a small amount of overlap between the consent requirement and the schema const.

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 non-idempotent, session-issuing, single-hour credential tool with no output schema, the definition covers the token return shape, storage and transport rules, the non-idempotency caveat, and the conditional-issuance failure modes. Nothing an agent needs to call it correctly is missing.

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 schema already documents each parameter including the consent const and agent_type enum. The description still adds useful semantics by emphasizing that consent must be explicitly true, that model disclosure is optional and self-declared, and that a non-HTTPS profile_url is not retained as a profile link. That goes slightly beyond repeating 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?

This states a specific verb and resource: create an opt-in attributed participant identity and a revocable one-hour session. It distinguishes itself from siblings like close_cassie_session by making clear this is the registration/entry step that precedes authenticated contribution tools.

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?

It says explicitly that explicit consent=true is required and that the token should be used with authenticated contribution tools, which routes the agent to the right sequence. It also warns not to assume a session was issued on consent, rate-limit, or feature rejection, which covers the failure path an agent would otherwise mishandle.

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