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

Annotations (readOnlyHint=false, openWorldHint=true, destructiveHint=false) cover the safety profile, and the description adds genuinely non-redundant behavior: the check runs in the background, returns a workflow ID and Studio URL rather than a result, and mirrors `rover subgraph check`. It does not mention authorization/permission requirements for the graph or variant, which is the main remaining gap.

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-loaded with the action and the async caveat, then the required inputs, then optional ones — a logical ordering. Five sentences, nearly all load-bearing; the 'rover subgraph check' comparison is helpful rather than 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?

For a non-trivial async mutation with 6 parameters, the description covers the action, async semantics, next step, and every parameter. The output schema exists so return values needn't be described, and the description mentions them anyway as a bonus; only permission/ownership preconditions are unaddressed.

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 0%, so the description carries the full burden — and it does: it names all four required inputs (graph ID, variant, subgraph name, proposed subgraph schema) and specifies the schema must be SDL, plus explains that branch and commit are optional labels for the run in Studio. That is meaning the bare schema does not provide.

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 — starts a schema check of one proposed subgraph schema against a variant — and anchors it to a familiar equivalent ('the same check that `rover subgraph check` starts'). It implicitly separates itself from the sibling RunSchemaCheck by emphasizing 'subgraph schema', but never names that sibling or states the distinction outright.

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?

Clear on the call flow: the check is asynchronous, and the returned workflowID must be passed to GetCheckResults to read the outcome, which routes the agent correctly to a named sibling. It does not say when to prefer this over RunSchemaCheck or LintSchema, so the exclusion side of the guidance is missing.

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