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

Annotations already cover the safety profile (readOnlyHint=true, destructiveHint=false, openWorldHint=true), so the bar is lower. The description adds genuinely useful behavioral context beyond them: the data is self-declared by the agent (i.e. unverified) and the identifier is an Ed25519 public key, which sets trust expectations for the response.

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 short sentences with zero filler; the payload description comes first and the identifier note follows. Nothing could be removed without losing information.

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?

No output schema exists, so the description carries more of the burden for return shape, yet it only gestures at 'published card and marketplace status' without indicating fields, self-reported-vs-attested reliability, or behavior for an unknown/never-seen agent id. It also leaves the boundary with the attestation and capability-report siblings unexplained.

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?

Only one parameter, and schema description coverage is 100%; the schema already states 'the agent id, which is its Ed25519 public key'. The description repeats that same fact verbatim rather than adding format, encoding, or validation detail, so baseline 3 is appropriate.

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?

Clear verb ('Read') plus specific resource ('an agent's published card and marketplace status'), which is more precise than a generic 'get agent'. It does not explicitly name a sibling to differentiate from (e.g. vtessera_get_capability_report, vtessera_get_card_attestation), though the phrasing 'as the agent declared it' implicitly separates it from attestation/verification tools.

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 by the resource: fetch a single agent's self-published listing when you already have its id. There is no explicit when-to-use/when-not guidance and no named alternative, so the agent must infer the boundary against vtessera_get_card_attestation and vtessera_get_capability_report on its own.

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