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

Annotations already cover safety (readOnlyHint, openWorldHint), and the description adds genuinely non-structural facts: the dataset refreshes twice a day, results are capped at 20 per call, cost is $0.002 USDC per successful call via x402 with failed calls not charged. It does not describe pagination or what happens when results exceed the cap, which is the remaining behavioral gap.

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-loaded with the resource and its fields, then search behavior, then the sibling disambiguation and pricing. It is dense but every clause carries information; the payment sentence is long and slightly secondary to task selection, keeping it from a 5.

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 an output schema present, return values need not be explained, yet the description still enumerates the fields, and it covers refresh cadence, result cap, and cost. For a two-parameter read tool this is nearly complete; only failure/empty-result behavior is unaddressed.

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 q and max are already documented including bounds and default. The description only restates that the search matches name or active substance, adding no format or syntax detail beyond the schema. Baseline 3 is appropriate.

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 resource (EMA centrally authorised human medicines) plus the exact fields returned (name, EMA product number, status, active substance, ATC code, indication, first authorisation date, holder) and the query mode (searches name or active substance). It also names the sibling it is not for, so an agent can route without opening either schema.

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 routes the agent to health_ema_shortages_safety 'when you need European Medicines Agency human medicine supply shortages', which is a clear alternative-use statement. It lacks any statement about when this tool is a poor choice (e.g. non-EU medicines) or what to do if the query returns nothing, so it stops short of the full when/when-not pair.

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