A2A Passport — one GTIN, one call, everything GSC knows, signed

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

The description adds real context beyond the annotations: it is 'read live ... on every call' and 'the first call issues version 1', which explains why readOnlyHint=false (a write side effect on first call) while idempotentHint=true. It does not discuss auth/permissions or failure behavior, but the annotation-consistent side-effect disclosure is valuable.

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?

Front-loads the return content, then the live-read/versioning behavior, then the parameter meanings. Dense but each clause earns its place; only the parenthetical GTIN explanation is slightly redundant.

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 an output schema present the return shape need not be explained, and annotations cover the safety profile; the description supplies the side-effect/versioning nuance and both parameter meanings. Only default-value and permission details are absent.

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 0%, so the description carries the burden and does document both params: subject is a GTIN of 8-14 digits or a market/banner string, and kind is 'gtin or banner (optional)'. It does not state what kind defaults to when omitted, a small remaining gap.

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+resource ('get the signed passport') and enumerates the payload it returns (holding hub, clearance, compliance records, listing, payment door). It is clear what the tool does, but it never names or distinguishes itself from the sibling list_passports or verify_passport.

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: retrieving the passport for a single subject ('a GTIN ... or market/banner'). There is no explicit when-to-use versus verify_passport or list_passports, and no statement of when this tool is not appropriate.

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

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

Annotations already declare this a safe, idempotent, non-destructive read, so the bar is lower. The description adds genuinely useful traits beyond them: fixed ordering ('newest first'), payload shape ('No bodies'), and that the result set is paginated.

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 compact sentences with no filler; the return shape and ordering come first and the filtering/pagination note follows. Every clause carries information an agent can act on.

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?

An output schema exists, so return values need not be spelled out, and the annotations cover the safety profile. The only real gap is the semantics of limit/offset, which are never explained beyond the word 'paginated'.

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 0%, so the description must carry the load and it does add meaning for kind (including the gtin/banner values the schema lacks an enum for), market, and since. It leaves limit and offset unexplained apart from the word 'paginated', so the compensation is partial.

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 (list) and resource (passports on the register) and enumerates exactly what comes back (ids, kinds, markets, versions, issue times). The contrast with siblings is implicit via 'No bodies,' which suggests get_passport returns the body, but no sibling is named outright.

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?

It tells the agent how to narrow results (kind, market, since) and that results are paginated, which implies usage for metadata browsing rather than fetching a single record. However, it never says when to prefer this over get_passport or verify_passport, leaving the agent to infer the routing.

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

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

Annotations already establish readOnly, idempotent, non-destructive, closed-world behavior, so the bar is lower; the description still adds meaningful context by disclosing the trust anchor used (the published key at /.well-known/jwks.json) and the four distinct checks performed. It does not state failure modes (e.g., what a broken chain returns), which is a minor gap.

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 dense sentences with the four checks front-loaded and the key-location detail placed last; no filler. The list-style phrasing is efficient, though the compressed 'was any section not read' clause reads slightly awkwardly.

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?

An output schema exists so return values need not be explained, and annotations cover the safety profile. However, with 0% parameter coverage and no usage routing to the sibling tools, the definition leaves real gaps for a two-parameter verification tool.

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 0%, so the description must carry parameter meaning, and it largely does not. The phrase 'chain of versions intact' loosely gestures at the optional 'version' parameter but never explains that it pins verification to a specific version, and the passport_id format/source is never described.

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 (verify/check) and resource (passport) and enumerates exactly what is validated: signature validity, version-chain integrity, stamp age, and unread sections. It is clearly distinguishable from get_passport/list_passports in intent, though it never names those siblings explicitly.

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 implied — this is the tool you call to validate rather than merely retrieve a passport — but there is no explicit when-to-use, when-not-to-use, or reference to the get_passport/list_passports alternatives. An agent can infer the routing but must do so unaided.

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