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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false, so safety is covered; the description adds real value on top by disclosing data provenance ('the figures are each provider's published ones') and the scope limit that only services, never medicines, are compared. It does not discuss latency or result completeness, so 4 rather than 5.

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?

Dense but well ordered: comparison targets first, then clinic attributes, then pharmacy attributes, then use cases, then boundaries. It slightly over-enumerates return fields that a separate output schema already covers, which is the only inefficiency.

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 dual-mode tool with 5 parameters and an output schema, the description covers the mode switch, the 2-6 slug constraint, mode-specific inputs, comparison dimensions, and data provenance. Since an output schema exists, it is not obligated to describe return shape further, and 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 baseline is 3, but the description adds meaning the schema does not: it ties patientType/followUpsPerYear/prescriptionsPerYear to a computed 'line-by-line breakdown for the patient type and visit counts you give' and marks these as clinic-only inputs. Slug semantics are left to the schema.

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 (compare) and resource (clinics or pharmacies) with cardinality and keying method ('two to six ... side by side by slug'). It also enumerates exactly which attributes are compared per provider type, so an agent can distinguish it from find_clinics/find_pharmacies without opening the 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?

Gives concrete user-intent triggers ('which is cheapest', 'what's the difference between') and an explicit when-not boundary ('it never compares medicines or medicine prices'), plus the constraint that clinic and pharmacy cannot be mixed. It does not name sibling tools as alternatives or say when to prefer two get_listing calls over this, so it falls short of a full 5.

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