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

Annotations already declare readOnlyHint=true (which the description redundantly restates as 'Read-only'), so the safety profile is covered. Beyond that, the description adds real value by disclosing that it replays the create lane's validation, lists the check categories, and explains the dependency_review signal for multi-member specs with no declared parents. It does not discuss cost/latency of the replay, but the behavioral picture is largely complete.

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 action and its non-destructive scope, then the check list, then the return contract and usage directive. Slightly dense but every clause carries information; no filler.

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 present, the description carries the return-shape burden and does so: it names {valid, errors} and explains the extra dependency_review field including the race condition it warns about. Combined with the read-only annotation and full schema, nothing needed to call this 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 the baseline is 3. The description earns above baseline by telling the agent the stack object is 'the same shape create_stack accepts, including each member's parents dependency edges' — a cross-tool contract that no single schema field states outright.

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+resource ('Validate a stack specification against the cluster') and immediately scopes it with 'without creating or deploying anything', distinguishing it from create_stack and from the cluster-manifest validator. It also enumerates the checks performed (duplicate stack name, member shape, chart and dependency checks), so an agent knows exactly what class of tool this is.

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?

Gives explicit ordering guidance: 'Use this before create_stack, and add the missing parents before deploying.' It names the alternative it precedes and the corrective action to take on failure, so the when-to-use condition is unambiguous.

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