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

readOnlyHint=true is already in annotations (the trailing 'Read-only' is mild redundancy, not a contradiction). Beyond that it discloses the return contents and an important edge case: an org that never declared a policy returns 'none declared' and services fall under the open default, a state shared only by other undeclared clusters. Given no output schema, this is valuable behavioral 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?

Front-loads the core purpose and then elaborates the return contents and edge case. Every clause carries information, though the final clause about which clusters share the default 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?

For a one-parameter read tool with no output schema, it covers what the response contains, the significant undeclared-policy case, and the related mutator needed to change the policy. Nothing an agent needs to call it 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?

Single parameter with 100% schema description coverage ('Cluster id (UUID) from list_clusters'), so the schema fully documents it. The description adds no further meaning about cluster_id, 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?

Uses a specific verb (Read) + resource (cluster's managed-service placement policy) and enumerates the concrete contents: region, data boundary, local-only flag, and revision. It explicitly distinguishes itself from its mutating twin set_service_cluster_policy, which also appears as a sibling, so an agent can route correctly without opening a 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?

Clearly frames this as the read side and points at set_service_cluster_policy for making changes, plus notes the negotiation context ('the revision set_service_cluster_policy needs to change it'). It gives a condition (undeclared clusters) but stops short of an explicit when-to-use/when-not-to-use rule.

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