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

While annotations include destructiveHint=true, the description adds critical context: 'Irreversible — DESTROYS all data on it,' which goes beyond the annotation. It also discloses the attachment constraint, providing fuller behavioral transparency.

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?

Two sentences, front-loaded with the core action, followed by warnings and a constraint. The REST endpoint is a minor but useful addition. No wasted words.

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 simple one-parameter delete operation with destructive annotations, the description covers the action, irreversibility, and a critical precondition. With no output schema, no further return-value explanation is needed. This is complete.

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 input schema has 100% coverage with the description 'The filesystem id to delete.' The description merely says 'by id' and adds no additional semantics beyond the schema, so the baseline of 3 applies.

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 'Delete a persistent filesystem by id' with a specific verb and resource, and includes the REST endpoint. This distinguishes it from sibling tools like lambda_create_filesystem and lambda_list_filesystems.

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 states a precondition: 'The filesystem must not be attached to any instance,' which serves as a when-not-to-use condition. It does not name alternatives, but none exist among siblings for this operation.

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