permissions_explain

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

Annotations already declare readOnlyHint and destructiveHint=true, and the description reinforces this with 'this tool is read-only.' It goes beyond annotations by detailing the return structure (allowed, effective_permissions, decision_trace, etc.) and explaining that allowed:null means insufficient evidence, which is valuable contextual behavior not present in structured data.

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?

The description is well-organized with clear sections (Purpose, When to use, When NOT to use, Returns) and is appropriately sized. Every sentence delivers essential information—scope, usage boundaries, and output meaning—with no filler or redundancy.

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?

Given the tool's complexity (8 parameters, permission hierarchy, multiple action types), the description provides sufficient context for an agent to select it correctly: it explains the exact use cases, limitations, and output semantics. The output schema also exists, so return format is covered; the description adds crucial interpretation details like allowed:null.

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 baseline is 3. The description does add some context (e.g., 'one guild member or one role' hints at mutual exclusivity), but it does not provide per-parameter semantics beyond what the schema already includes. Thus it meets the baseline but doesn't exceed it.

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 opens with a specific statement: 'Explain effective Discord permissions for one guild member or one role.' This identifies the verb (explain), the resource (Discord permissions), and the scope (member or role), which clearly distinguishes it from siblings like permissions_audit_channel or mutating tools.

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?

Explicit 'When to use' and 'When NOT to use' sections are provided. It states to use before writes for verification and diagnosis, and explicitly excludes mutating roles/overwrites or treating partial results as permission to write. This gives clear decision guidance without needing to infer.

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