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

The annotations already declare readOnlyHint=true, and 'Read-only' merely restates that. The only added behavioral detail is the GraphQL mapping 'query user(id)', which aids implementation understanding but says nothing about not-found behavior, permissions, or which user types are actually resolvable.

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?

Three short sentences, all front-loaded with the core action first and zero filler. Every sentence carries distinct information (purpose, safety, call mapping).

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 one-parameter read tool with annotations covering safety and no output schema, the description is nearly sufficient. The minor gap is that it does not hint at what the returned user object contains or whether the id namespace is shared between patients and providers.

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 single id parameter is documented in the schema, so the baseline is 3. The description's only added semantic is that the id may identify a patient or a provider, which is marginal value over 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?

States a specific verb and resource ('Fetch a single user') and clarifies that the entity may be a patient or a provider, which helps separate it from healthie_list_patients and healthie_current_user. It does not explicitly name those siblings, so differentiation is implicit 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?

'by id' plus 'Read-only' implies this is the lookup path when you already have a user id, and the singularity of the fetch rules out the list tools. However, it never states when to prefer this over healthie_current_user or healthie_list_patients, and gives no preconditions.

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