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

With no annotations, the description carries the full behavioral burden. It usefully discloses that the output is educational and species-scoped rather than diagnostic, but says nothing about whether reference values are static vs. dynamic, pagination, or the shape of the returned explanation.

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 tight sentences with the core action front-loaded and the scope-limiting caveat ('Educational only') closing it. No filler.

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, the description does explain what the agent can expect back (measurement meaning, importance, reference context). It is nearly complete for a simple read-only lookup tool, missing only return-format detail.

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%, so both parameters (biomarker code/name, optional species) are already documented in the schema. The description adds only that reference context is species-specific for dogs and cats, which is marginal over the schema's enum.

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 (explains) and resource (lab biomarker), and enumerates what the explanation covers: what it measures, why it matters, and reference context. 'Educational only' partially separates it from interpret_lab_report, but it never names the siblings 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?

The phrase 'Educational only' implies usage (reference/lookup, not diagnosis), which is useful context. However, it never states when to choose this over interpret_lab_report or suggest_retest_timing, leaving the routing decision to inference.

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