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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=true, so safety is covered. The description adds real value beyond them: it discloses that the payload is protected health information, itemizes the PHI categories, and explicitly states the SSN is never returned - a genuinely useful privacy/redaction guarantee. It stops short of noting auth requirements or behavior when the id is not found.

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?

A single dense sentence, front-loaded with the core purpose and the id requirement, ending with the underlying REST route. The field enumeration is long but each item earns its place by telling the agent what PHI comes back.

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 enumerating the returned data categories, and it covers the id format, the privacy guarantee, and the endpoint. For a one-parameter read tool this is as complete as an agent needs.

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% and the schema provides the pattern regex, so baseline is 3. The description improves on it by giving a concrete example identifier format (pat-ab12C345DeF6), which helps an agent recognize and validate the id, though it adds no further syntax rules.

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 ('One patient by id') and enumerates exactly what is returned (identity, contact, address, insurance, consents, memberships, sponsorships, emergency contact), which clearly separates it from the list_/match_ siblings. It never explicitly names those alternatives, so the differentiation is inferable rather than stated.

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?

Usage is implied: 'by id' signals the tool requires a known patient identifier, which distinguishes it de facto from hinthealth_match_patients and hinthealth_list_patients. There is no explicit when-to-use / when-not-to-use statement nor any pointer to the sibling tools for the other lookup modes.

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