Start my Phi Longevity account (emails me a sign-in link)

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

Goes well beyond the supplied annotations: it discloses the email/link delivery mechanism, that "Nothing attaches to their account until they confirm; unused, it is deleted after 3 days," and that "The answer is the same whether or not they already have an account" — directly explaining the non-idempotent, open-world behavior. The privacy guardrail ("never lab values, names, birth dates or documents") adds consent/PII handling not encoded anywhere in the structured fields.

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 outcome (sign-in link) and the consent gate, then layers the pre-population and retention details; almost every sentence carries operational weight. The opening tagline "Every doctor, your complete record" is mild product framing rather than instruction, the only genuinely dispensable clause.

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?

With an output schema present, the description needn't explain returns, and it nonetheless warns that the response is identical for existing and new accounts. For a 5-parameter, nested-object, open-world tool it covers the consent gate, data provenance, retention, and PII limits — everything an agent needs to invoke it safely.

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 already 100%, so the schema defines each field; the description adds provenance the schema lacks by tying hospitals to get_my_medical_records, job_ref to prepare_for_my_appointment, and care_gaps to check_care_gaps. It also restates the content restriction ("Hospital names and closed options only"), reinforcing the schema's "closed options only" note.

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 and resource ("Start my Phi Longevity account" / "call this with their email address") and immediately explains the effect: "Phi Longevity emails them a one-tap sign-in link (no password, free to start)." It is clearly distinguishable from the read-only siblings like get_my_medical_records and check_care_gaps, which it names as data sources rather than alternatives.

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?

Gives an explicit trigger ("When the person you are helping wants their own Phi Longevity account") and a hard prerequisite ("ask them first; never call it without their clear yes"). It also tells the caller what to pre-populate from which sibling tools. It does not explicitly contrast against how_to_get_started_for_my_owner, so the alternative-routing is inferred rather than stated.

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