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

Annotations already declare readOnly=false and non-destructive; the description adds real value beyond them by naming the required permission (clusters.write), the durability of the binding ('every setup on the cluster is held to it'), and the reserved-word constraint. The expected_revision mechanism also conveys optimistic-concurrency behavior consistent with idempotentHint=false.

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?

A single dense paragraph that is front-loaded with the core purpose before unpacking semantics and constraints. Every sentence carries information, though the parenthetical CLI reference is slightly verbose.

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 mutation tool with no output schema, it covers permission requirements, optionality, the default state, revision handling, and reserved-value behavior. A comparison of when to declare vs leave unspecified is only implied rather than stated.

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 100%, so the baseline is 3, but the description adds genuine meaning by explaining expected_revision's source (get_service_cluster_policy) and the 0-creates-only-if-absent rule, and by reinforcing the region vs data_boundary distinction used for consumer serving.

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 (declare) and resource (a cluster's managed-service placement policy), and immediately distinguishes its scope from the read counterpart (get_service_cluster_policy). An agent can tell exactly what this does and how it differs from sibling policy 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?

Explains that declaring is optional, what happens without one (open `unspecified` default), and that a declared policy binds all future setups. It routes to get_service_cluster_policy for the revision value, but stops short of an explicit 'use this when X, not Y' comparative statement.

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