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

Annotations only declare readOnlyHint and openWorldHint=false, so the description carries real added weight: it discloses result ordering (cheapest first), that stock is included, that alternative brands are returned, and a data-freshness caveat ('prices refresh every 6 hours: don't memorize them'). That freshness/ordering context is exactly what annotations cannot convey.

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?

Three tight sentences, front-loaded with what the tool returns, then accepted inputs, then a freshness caveat. No filler and every sentence carries information an agent needs.

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 must characterize the return payload, and it does: prices, stock, and same-active-ingredient alternatives in ascending price order. It is slightly thin on edge cases (unknown drug, how many pharmacies are covered), but otherwise complete for a one-parameter read tool.

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 coverage is 100% and the single parameter's description already supplies examples for all three accepted forms (brand, active ingredient, name with dose), which the prose merely restates. Baseline 3 is appropriate since the schema does the heavy lifting.

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 and scope: prices of a medication across Chilean pharmacies, sorted cheapest-to-most-expensive, including stock and alternative brands with the same active ingredient. It is immediately distinguishable from a generic lookup, though it never explicitly contrasts itself with siblings like ficha_medicamento or marcas_mismo_principio, whose territory it partially overlaps.

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?

Usage is implied (call this to get prices), and it usefully lists accepted input forms and warns that prices refresh every 6 hours. However, it gives no explicit when-to-use vs when-not guidance and never names an alternative tool for cases where the user wants drug info rather than price.

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