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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so the safety profile is covered. The description adds useful behavioral context: there is 'No account or API key', the data is a 'fixed fictional sample EMR', and results are normalized from FHIR R4. This goes beyond the structured annotations without contradicting them.

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 three sentences with no filler. It front-loads the core purpose, adds the data source detail, and then gives the alternative tool guidance. Every sentence earns its place.

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 zero-parameter, read-only tool with a rich annotation set and an output schema, the description covers what an agent needs to select and invoke it correctly. It states the scope, the synthetic nature, the lack of auth requirements, and how to get broader results, leaving no critical gap.

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?

The input schema has zero parameters and 100% coverage, so there is no parameter detail for the description to add. The baseline of 4 applies, and the description contributes relevant access context by noting no account or API key is required.

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 uses a specific verb and resource: 'get only the lab results (labs)' of FinchNode's fixed fictional sample EMR. It also names the data source and normalization standard (FHIR R4 Observation, DiagnosticReport), making the tool's purpose unambiguous. It further distinguishes itself by explicitly noting it returns only labs, not other categories.

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 explicitly states when to use this tool: when only lab results are needed. It also gives a clear alternative and condition: 'To get lab results together with other categories, call get_demo_health_record once instead of calling several of these tools.' This provides actionable routing guidance beyond simple purpose.

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