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

Annotations declare readOnlyHint=true, and the description goes well beyond that with a non-obvious interpretation rule: null over_policy/impersonate_reachable means 'could not establish that count... never 0, so report it as unverified rather than clean.' This directly prevents an agent from misreporting a null as a clean result.

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?

Three sentences, front-loaded with the resource and its contents, then the critical null-handling caveat, then the use case. Dense and mostly waste-free, though 'Read-only' duplicates the annotation and the return-field enumeration is lengthy.

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?

There is no output schema, so the description carries the return-value burden and does so thoroughly, describing each returned field group plus the null semantics of access_posture fields. Nothing an agent needs to interpret the response correctly is missing.

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 100%, so page/sort/order/search/status/page_size are already documented in the schema. The description adds no syntax or format detail about these filters, so the baseline 3 applies.

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 resource and scope ('per-cluster security posture across the fleet') and enumerates the returned dimensions (finding counts by severity, known-exploited count, scanner coverage/freshness, Kubernetes access posture). The fleet-wide framing distinguishes it from per-cluster security tools in the sibling set. An agent can tell what it returns without opening the schema.

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?

'Use to find the clusters driving the organisation's exposure' gives a clear selection context. It does not name alternative tools (e.g. get_security_overview, list_security_findings) or state when NOT to use it, so it stops short of the explicit when/when-not/alternatives bar.

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