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

Annotations already declare readOnlyHint=false, destructiveHint=false and openWorldHint=true, so the mutation profile is covered. The description adds context the annotations do not: what each optional-parameter combination produces and that the call yields the new comment ID/message or an error. It stops short of stating permission requirements or validation failure modes.

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 purpose, then the mode-selection rules, then the return and required-input note. Slightly redundant at the end: it restates the required inputs (graphId, proposalVariant, revisionId, message) and describes the return value despite an existing output schema.

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 7-parameter mutation with zero schema description coverage, the description is nearly complete: all parameters are explained and the reply/change/general modes are distinguished. The only gap is operational context such as required permissions or what happens when an invalid coordinate is supplied, beyond the generic 'error with a message'.

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 carry the load — and it does, explaining essentially all seven parameters: graphId, proposalVariant, message, revisionId (with its source), schemaCoordinate (with a concrete 'Query.products' example), schemaScope (subgraph name), and parentCommentId (reply targeting). The pairing of schemaCoordinate and schemaScope is implied directly in the sentence that names both.

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 ('Add a comment to a schema proposal') and anchors it to the equivalent UI action in GraphOS Studio. No sibling tool in the list deals with proposal comments, so the boundary is unambiguous.

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?

Explicitly enumerates three usage modes and the condition that selects each: bare call for a general comment, schemaCoordinate + schemaScope for a change-level comment, parentCommentId for a reply. It also names the prerequisite source for revisionId ('latestRevision.id from GetProposal'), routing the agent to the correct upstream tool.

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