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

Annotations already declare readOnlyHint=true, so the safe-read profile is covered by structured data. The description adds the underlying HTTP shape (GET /{resource}/{id}), which is minor context but discloses nothing about error behavior, authentication, or missing-resource handling.

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?

Two short sentences, front-loaded with the action and resource, with zero filler. The trailing GET path line is compact and bounded.

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 two-parameter read with a fully documented schema and annotations covering the safety profile, the definition is sufficient to invoke correctly; no output schema exists, so return-value explanation is not expected. Only the absence of explicit sibling routing keeps it from being complete.

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 100% and both parameters (id, resource with a 36-value enum) are documented in the schema itself. The description merely restates 'by type and id' and adds no format, casing, or id-syntax guidance beyond 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?

The description gives a specific verb and resource ('Fetch a single FHIR resource') plus the parameters needed ('by type and id'), and the word 'single' implicitly contrasts with a search/list operation. It stops short of naming the sibling (canvas_search) it differs from, so an agent must infer the boundary.

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 only implied: an agent can infer this is the tool to use when it already knows the resource type and id. There is no explicit statement of when to prefer canvas_search or canvas_get_patient_everything instead, and no prerequisites noted.

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