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

Annotations already declare readOnlyHint, idempotentHint, and openWorldHint=false, so the safety profile is covered. The description adds that the result includes check digit status, which is real behavioral value, but with no output schema it says nothing about the returned shape (e.g., type plus validity fields) or what happens for an unrecognized string.

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?

One front-loaded sentence that states the action first and then the accepted formats, with no filler. The long format enumeration is functional scope-setting rather than padding, though it is dense enough to read as a list dump.

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 read-only, idempotent, single-parameter tool this covers the essentials, and check digit status is disclosed. It is still thin on outcome behavior — no statement of what is returned for unknown codes or the response structure — which matters because there is no output schema.

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?

There is a single parameter with full schema description coverage, so the baseline is 3. The schema already says the code is taken exactly as printed or scanned, and the description's format list mildly reinforces what inputs are accepted without adding parsing or format details beyond that.

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?

Names a specific verb ("find out what kind of code") and an enumerated set of supported formats (GTIN, ISBN, ISSN, SSCC, GLN, GS1-128, Digital Link, VIN, IMEI, ASIN, LPN, FNSKU), which makes the scope unmistakable. It doesn't contrast itself against siblings like validate_gtins or parse_gs1, so the boundary is inferred from the enumeration rather than stated.

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 only implied: an agent can infer this is the tool for an unknown code, but the description never says when to pick it over validate_gtins, parse_gs1, or check_amazon_code, nor does it state any preconditions. No exclusions or sequencing guidance is given despite a crowded sibling set.

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