Full multi-track report (paid developer option, $4.99 USDC via x402)

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

Goes well beyond the annotations: discloses the two-step x402 payment handshake (call without `payment` → receive terms → retry with base64 payload), the exact price and chain, and a retention policy (nothing stored except an optional claim link holding values up to 30 minutes). The non-idempotent hint is effectively explained by the pay-per-call model. Minor tension: a charging tool with temporary value retention is arguably not purely read-only, but this is disclosed rather than contradicted.

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-loaded with the paid nature and capability, then payment mechanics, then safety/retention constraints — a sensible order. It is dense and slightly repetitive (price appears in both title and body), but nearly every sentence carries operational information an agent needs.

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 no output schema, the description compensates by naming the return artifact (rendered markdown report plus score breakdown). Together with the payment flow, data-handling caveats, and PHI prohibition, an agent has everything needed to call this correctly on the first try.

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 every field; the description still adds real meaning by explaining the `payment` parameter's protocol semantics that the schema only hints at ('omit on first call to receive payment terms'). It also reinforces the 'up to 4 condition tracks' bound on compareTracks.

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 ('runs up to four condition tracks ... returns a written report') and explicitly positions itself against a sibling ('Everything explain_my_lab_results does, plus: multi-track compare/contrast analysis...'). The added scope items (Phi Longevity Score with per-pillar breakdown, partner options, markdown report) make the differentiation concrete rather than generic.

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 explicit when-to-use (developers, synthetic/de-identified values, research/education) and when-not (real person's own records → philongevity.com; no PHI). It also names the superset relationship to explain_my_lab_results, so an agent can trade cost against feature scope.

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