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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered; the description adds real value by disclosing the required input provenance (the report's own range, not a default) and the scope limit that it does not interpret or diagnose. It also sketches the shape of the answer (inside/below/above plus a pointer). Beyond that it says nothing about missing-range behavior or precision/rounding.

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 sentences, front-loaded with the outcome, then the input constraint, then the scope limit. No filler; every sentence carries information an agent needs.

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 and full parameter coverage, the description covers purpose, required inputs, and the diagnostic-scope boundary. The remaining gap is what happens when neither range_low nor range_high is supplied, since those are optional.

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%, so the baseline is 3, but the description genuinely adds semantics the schema lacks: range_low/range_high must be taken from the person's printed report because reference ranges are lab-specific. That is a meaningful constraint on how to populate two optional parameters.

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: it compares an exam value against the reference range printed on the person's report and returns inside/below/above, plus a pointer to where to understand the result. It implicitly separates itself from ask_health_guidelines by saying 'Não interpreta nem diagnostica', though it never names a sibling explicitly.

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?

Gives clear operational guidance — pass the range from the report itself via range_low/range_high, because ranges vary by laboratory and a generic range is not used. It also sets a boundary ('não interpreta nem diagnostica'), which tells the agent when to hand off. It does not name the alternative tools or state exclusions by name.

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