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

Despite annotations already covering the safe-read profile (readOnlyHint, idempotentHint, destructiveHint=false), the description adds substantial value: it warns the response is untruncated and can exceed 800,000 characters (~200,000 tokens), and that a non-federated variant returns null rather than an empty document. These are non-obvious behaviors an agent needs.

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 core purpose, then context, then size/edge-case warnings, then parameter reminder. Efficient overall, though the size warning is stated slightly redundantly across two sentences ('is not truncated... larger than the API schema' followed by 'Expect the same order of size...').

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?

An output schema exists, so return-value formatting need not be described, yet the description still covers size, null behavior, and error inclusion. Nothing an agent needs to invoke this correctly in a complex federated-graph context 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 0% for both parameters. The description says 'Provide the graph ID and the variant name,' which identifies both params but adds essentially no semantics beyond their names (no format, no acquisition guidance). It slightly compensates for the empty schema but leaves gaps, so a 3 is 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?

States a specific verb and resource ('Read the composed supergraph schema (SDL) for a graph variant') and distinguishes it from related schemas by noting it 'carries federation directives that the API schema does not.' An agent can tell it apart from GetGraphSchema/GetSubgraphSchema without opening any 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?

Gives clear context by equating it to `rover supergraph fetch` and contrasting supergraph vs API schema output, which implicitly routes the agent. However it never explicitly names the alternative sibling tools (GetGraphSchema, GetSubgraphSchema) or states when NOT to use this one, so it stops short of full when/when-not guidance.

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