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

Goes well beyond the annotations (readOnlyHint=false, destructiveHint=true) by detailing exact-string comparison, refusing wildcard widening, refusing clearing to empty, and requiring edit access. These are behavioral traits the agent needs to know and are not in the schema.

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 front-loaded with the purpose and then packs in necessary edge cases. It is dense but not padded. The complexity justifies the length; every sentence contributes essential context.

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?

Despite no output schema, the description covers the full operational context: current list source, narrowing-only constraint, refusal scenarios, access requirements, and the web-only alternative for widening. This is complete for a tool with this complexity.

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?

The schema already covers the param definition and subset requirement, but the description adds critical semantics: strict subset/equal comparison, exact-string matching, and refusal of wildcard expansion. This meaningfully supplements the schema, though the schema coverage is high.

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 verb and resource: 'Narrow the project's outbound host allowlist.' It clearly distinguishes itself by emphasizing this tool only narrows, never widens, which differentiates it from any potential sibling or web-based action.

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?

Provides explicit guidance: widening is 'web-only, in the panel,' so this tool is for narrowing. It tells users to check the current list via get_project, and states clear refusal conditions (existing targets outside the submitted list). This is strong when-to-use/not-use guidance.

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