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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=true, so the safety profile is covered; the description adds genuinely new behavior by disclosing the NOT_PROBED error for never-probed agents and that the probe is signed. It does not say whether results are cached or how freshness relates to the non-idempotent annotation, but the error contract is valuable added context.

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 tightly constructed sentences with the core purpose front-loaded and the error condition trailing. The clause 'which records whether it answered when checked' earns its place by defining the report's content, though it is slightly wordy.

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, the description correctly explains what the report contains and what happens in the empty case (NOT_PROBED), which is the key thing an agent needs to interpret the result. It omits any mention of response shape or staleness, which is a minor gap for a single-parameter read 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?

There is only one parameter and schema description coverage is 100%, so the schema fully documents agentId. The description adds no format, source, or constraint detail about the id beyond what the schema already provides, making the baseline 3 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?

States a specific verb and resource ('Read ... signed capability probe of an agent') and clarifies what the payload records ('whether it answered when checked'), which separates it from generic siblings like vtessera_get_agent. It stops short of explicitly contrasting itself with the closest sibling, vtessera_get_card_attestation, so an agent must infer the distinction.

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 scope ('the most recent ... probe'), and it usefully notes the failure precondition ('Fails with NOT_PROBED when the agent has never been probed'). However, it never says when to reach for this versus vtessera_get_agent, vtessera_get_card_attestation, or vtessera_health, so the agent gets no routing guidance.

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