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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds valuable behavioral context beyond that: matching is 'partial, case-insensitive match on the brand name', the tool is 'Keyless', and it returns a specific set of fields. It doesn't mention pagination or error behavior, but for a read-only search tool the disclosed behavior is solid.

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?

The description is compact and front-loaded: the core purpose and scope appear in the first sentence, followed by return fields, example questions, exclusions, matching behavior, and example calls. Every sentence earns its place, though the example calls and question list add a bit of length. It's slightly dense but well-organized and not bloated.

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 search tool with two well-documented parameters, no output schema, and no nested objects, the description covers the essential context: what it searches, what it returns, how matching works, and when to use alternatives. The only minor gap is that it doesn't describe the output format or pagination behavior, but the annotations and schema already cover the safety and parameter aspects, so the description is largely complete.

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 both parameters (brand_name and limit) with descriptions and examples. The description reinforces the meaning of brand_name by explaining the partial, case-insensitive matching behavior and providing example calls, but it doesn't add substantial new parameter semantics beyond what the schema provides. 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?

The description states a specific verb ('Search'), a specific resource ('Health Canada's Drug Product Database'), and the exact scope ('drugs authorised for sale in CANADA by brand name'). It also lists the return fields (DIN, brand name, company, class, last update) and gives concrete example questions, which makes the tool's purpose unmistakable and distinguishes it from the sibling tools like health_canada_drug_detail and health_canada_drugs_by_ingredient.

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 description explicitly says when to use this tool ('Answers "is Tylenol approved in Canada"...') and when not to use it ('for US approvals and labels use the openfda or dailymed packs'). It also names the sibling alternatives for related but different queries (health_canada_drug_detail, health_canada_drugs_by_ingredient), giving an agent clear routing guidance.

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