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

Annotations only declare the safety profile (readOnlyHint=false, destructiveHint=false, openWorldHint=true), so the description carries the real behavioral burden and does it: the check is asynchronous, it returns a workflow ID and Studio URL rather than a result, and the run can be labeled with branch/commit. This is exactly the kind of non-obvious trait an agent needs before calling.

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?

Six short sentences, front-loaded with what the tool does and what it returns, then routing, then parameter enumeration. Every sentence carries non-redundant information that is absent from the schema and annotations.

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?

Complete for a five-parameter async mutation: purpose, scope vs. sibling, return shape, and next-step tool are all covered. With an output schema present, the description needn't detail the payload, yet it still pre-empts the most likely misconception (expecting a synchronous result).

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 must compensate, and it does name all five parameters with meaning: graph ID, variant name, proposed schema as SDL, and optional branch/commit used to label the run in Studio. It stops short of format details (SDL syntax, variant naming conventions), so not quite a 5.

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 ('Start a schema check of a proposed schema against a variant') and anchors it to a known equivalent ('the same check that `rover graph check` starts'). It explicitly delineates scope against the sibling RunSubgraphCheck ('use RunSubgraphCheck for one subgraph').

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 an explicit when-to-use rule (monograph or whole supergraph schema) and names the alternative plus the condition that selects it (one subgraph → RunSubgraphCheck). It also routes the agent forward to GetCheckResults, so the full workflow is discoverable.

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