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

Annotations already cover the safety profile (readOnly, idempotent, closed-world), so the description's job is to add semantics — and it does: results are filtered by the GS1 check digit, and the return is a set of candidates rather than a single value, which tells the agent to expect multiple matches. It stops short of saying what happens when no candidate passes.

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 sentence that front-loads the use case and then the output contract. No filler, nothing repeated for its own sake.

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, no-output-schema tool this covers the essentials: input convention, validation criterion, and that multiple values can come back. Minor gaps remain around empty results and ordering of candidates.

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 parameter description already carries the wildcard convention and an example. The description restates the same '? or *' convention without adding format constraints such as length rules or mixed-wildcard limits, so 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 verb (recover) and resource (GTIN) plus the exact operating mode: wildcard digits with ? or *. That mechanism is unique among the siblings (validate_gtins, calculate_check_digits, parse_gs1), so an agent can route here without opening another 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 trigger condition is explicit: use this when a GTIN has unreadable digits. It does not name alternatives (e.g. validate_gtins for a fully known code) or state exclusions, so usage is clear but not fully disambiguated.

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