FHIR read

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

With no annotations provided, the description carries the full burden. It does disclose that a 404 means genuinely not found, which is valuable error semantics. It also indicates the response is FHIR R4 format. However, it does not mention authentication requirements, rate limits, or what happens on other errors (e.g., 401, 500). For a read-only GET operation, this is above minimum but not rich.

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 description is two sentences with no wasted words. The URL template is front-loaded, followed by a critical error-handling note and a cross-reference to search. Every sentence earns its place, making it highly efficient.

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 simple single-resource read, the description covers the URL construction, 404 semantics, and resource type allowlist. It does not explicitly state the tool's overall purpose (fetching one resource) or mention authentication, which might be assumed from a prior auth step. Given no output schema, it could also clarify the response shape, though 'FHIR R4' implies a FHIR resource. Slight gaps remain in purpose clarity and auth context.

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 description coverage is 0%, so the description must compensate. The URL template '{iss}/{resourceType}/{id}' gives meaning and ordering to the three parameters, and the allowlist note constrains resourceType. However, it does not explain what iss represents (likely the server base URL) or any format expectations for id or resourceType beyond being strings. This is partial compensation for the lack of schema documentation.

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?

The description states 'GET {iss}/{resourceType}/{id} as FHIR R4', which clearly indicates a read operation targeting a specific FHIR resource. It also clarifies the 404 semantics, which helps distinguish it from a search that might return empty results. However, it does not explicitly say 'retrieve a single resource by ID', relying on the URL pattern to imply it, and it does not contrast with fhir_search directly beyond the allowlist note.

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?

The description provides no explicit guidance on when to use this tool versus fhir_search or other siblings. It only mentions 'Same resourceType allowlist as search', which hints at shared constraints but does not explain the core difference (single resource lookup vs query). A clear statement like 'Use this to fetch one resource by ID; use fhir_search for queries' is missing.

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