rbac__explain_access_denied

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

Beyond the readOnlyHint annotation, the description discloses that only missing console role names are returned and adds an important authentication caveat: the principal is usually the MCP service account, not the console user. This is valuable behavioral context an agent would not otherwise know.

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 short sentences, each earning its place: the action, the constrained output, and the auth-context caveat. The most important usage guidance is front-loaded before the auth note.

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?

The description is complete for a diagnostic tool with a rich output schema and fully documented parameters. It covers when to use it, what it returns, and a crucial identity caveat; nothing essential is missing for an agent to invoke it correctly.

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 input schema already documents all four parameters well. The description does not add parameter-level detail beyond the schema, which is acceptable given the high coverage baseline.

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?

The description clearly states the tool's job: diagnosing a 403 access denial for a specific MCP tool call and returning missing console role names. It does not explicitly name or distinguish sibling tools like rbac__lookup_tool_requirements or rbac__get_caller_access, so it stops short of full sibling differentiation.

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?

The description gives clear context for use: when a 403 occurs on a specific tool call, use this instead of guessing role or permission names. It does not explicitly contrast with sibling RBAC tools, but it provides actionable guidance about when the tool is appropriate.

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