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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered; the description adds the useful detail of which compliance areas are audited. However it never says what the result looks like (per-field findings, pass/fail, severity) and never explains that a URL mode performs a remote fetch, which sits in mild tension with openWorldHint=false. Adds value, but leaves the agent guessing about output behavior.

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 sentences, front-loaded with the action and followed by the regulatory context that justifies it; there is no filler. The second sentence is borderline but earns its place by telling the agent who is in scope and from when, which supports the required 'category' argument.

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 and 5 parameters at 40% coverage, the description should carry more weight than it does: it never describes the response shape of a 'check' or clarifies the optional 'model' field. It is adequate for choosing the tool but thin for interpreting results, so a 3 is appropriate.

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 only 40%, so the description must compensate; it does so for 'json', 'url' and implicitly 'mode' by naming the two input styles, and for 'category' via the EV/LMT/industrial scope sentence. The 'model' parameter is left completely unexplained in both schema and description, so the compensation is partial rather than complete.

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 and resource ('Check an EU battery passport') and anchors it to a named regulation, Regulation (EU) 2023/1542. It then enumerates the exact dimensions checked (scope, unique identifier, Annex XIII public fields, restricted-data exposure, state-of-health, carbon footprint), which is far more specific than any sibling tool and makes selection unambiguous.

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 input-shape guidance ('pasted JSON or a passport/QR resolver URL') and a scoping cue in the deadline sentence, which implies the check matters for EV, LMT and >2 kWh industrial batteries. It stops short of explicit when-not-to-use guidance or naming an alternative path (e.g. what to do for portable or SLI passports), so it falls just under a 5.

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