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

Annotations already declare readOnly, idempotent, and non-destructive behavior, so the bar is lower, but the description adds substantial context: it reports what instruments say, includes a verified_on timestamp, never raises protocol errors but returns an error object, and is safe to retry. This goes well beyond the structured annotations and gives the agent accurate expectations.

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 core purpose and uses the example and usage note effectively. It is slightly longer than necessary because it repeats the read-only/idempotent claims already present in annotations and includes the arguably unnecessary 'FREE' emphasis, but every other sentence earns its place.

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 zero-parameter listing tool with rich annotations, the description is complete: it gives a concrete response example, explains when to use it, discloses limitations, specifies error behavior, and confirms retry safety. An agent has everything needed to call 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?

The tool has zero parameters and the schema already documents an empty object. The description reinforces this with 'Typical input {}' and explains the shape of the response, which is helpful even though no parameter-level semantics are needed. This matches the 0-parameter 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 opens with a specific verb and resource: 'List the reporting regimes this server can compute, with citations.' This clearly identifies what the tool does and distinguishes it from the sibling compute/classify operations by framing it as the discovery step for regime ids and event_types.

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?

It explicitly says when to use the tool: 'Use when choosing the regime id and event_type for compute_deadlines or classify_event.' It also adds a clear non-purpose boundary ('Not for legal advice'). It does not explicitly name an alternative tool to use instead, but the usage context is strong enough to route an agent correctly.

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