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

Annotations already declare it is a read-only, idempotent, non-destructive, non-open-world tool, so the safety profile is covered. The description adds that these are fluids not medicine, that figures come from leaflets never from a model, and that it uses named sources (AEMPS, SEUP, Dioralyte). It does not discuss whether output varies by language or how conflicting sources are resolved, but it goes beyond annotations.

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?

Front-loads purpose, then sources, then usage condition and escalation route. Every sentence earns its place; no repetition of schema or annotation content.

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 read-only guidance tool with an output schema and fully documented parameters, the description covers purpose, sources, usage condition, and safety escalation. Nothing an agent needs to call it correctly is missing.

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 the schema already documents each parameter, including enum values and defaults. The description adds that only the age is needed and implies age-band branching, but does not add syntax or format beyond the schema. Baseline 3 is correct when schema does the work.

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+resource: how much oral rehydration solution to offer, volume per intake, frequency, and what to do if the child brings it back up. It distinguishes itself from siblings by naming paediatric_warning_sign_check as a prerequisite in a specific scenario.

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?

Explicitly states when to use it (child vomiting or has diarrhoea), what input is needed (only age), and the exact condition to use a different tool first (signs of dehydration or blood). This is clear when/when-not guidance with a named alternative.

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