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

Annotations already indicate the operation is idempotent and non-destructive. The description adds the auth requirement ('Requires an API key') and scoping, but it does not go into side effects, duplicate behavior, or other operational details beyond the annotations.

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?

Two tight sentences front-load the operation and scope, then provide syntax guidance and a prerequisite. There is no filler or redundant restatement of the schema.

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 simple two-parameter tool with full schema coverage and an output schema, the description covers the action, scope, syntax, and auth requirement. It could offer more detail on behavior for duplicate patterns or explicit exclusions, but annotations and schema carry much of that weight.

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%, so the baseline is 3. The description references the pattern syntax and search_product_recalls, but the schema already documents the same semantics; it adds little new meaning.

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 names the specific action ('Add') and resource ('recall watch pattern') and scopes it to an API key, making it clearly distinct from sibling tools like list_watch_patterns and remove_watch_pattern even 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?

The description gives clear context: use this to add a watch pattern scoped to an API key, and it points to search_product_recalls for the exact pattern syntax. It does not explicitly list when-not-to-use or alternatives, so it falls short of a 5.

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