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

Annotations declare readOnlyHint=true and openWorldHint=false, covering the safety profile. The description adds useful behavioral context by disclosing the data source (MINSAL) and the shape of the result (address, phone, map), which the agent cannot infer from annotations alone.

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?

A single dense sentence with no filler, front-loading the resource and its time/geographic scope before the source and returned fields. Every clause earns its place.

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 one-parameter read-only lookup with no output schema, the description is nearly complete: it names the scope, source, and returned fields. Only minor gaps remain (e.g., result ordering, whether results are limited), which are not essential for correct invocation.

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?

The single 'comuna' parameter is fully documented in the schema (100% coverage) with examples ('Providencia', 'Viña del Mar'). The description adds no syntax or format detail beyond what the schema already provides, so the baseline 3 applies.

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 (on-duty pharmacies), precise scope (today and open now, within a Chilean comuna), the data source (MINSAL directory) and the returned fields (address, phone, map). This clearly distinguishes it from the sibling tools, which concern drug pricing and medication records, not pharmacy locations.

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 'hoy y abiertas ahora' implicitly tells the agent this is for finding currently open on-duty pharmacies, giving clear context for when to reach for it. It does not name alternatives or exclusions, but the siblings are topically unrelated, so no explicit routing is needed.

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