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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so safety is covered structurally. The description adds genuinely new behavioral context beyond that: the tool is free and never triggers the $0.001 USDC paid endpoint, which is exactly the fact an agent needs before calling it repeatedly.

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 tight sentences plus a short disclaimer, front-loaded with what the atlas contains before the behavioral caveats. The standalone "Read-only" sentence is mildly redundant with readOnlyHint but is cheap and reinforces the point.

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?

With no parameters and no output schema, the description carries the burden of describing the return payload, and it does so by enumerating the action/target/owner/cap entries the atlas holds. What is missing is any hint of the response's shape or size (flat list vs. grouped atlas), but the coverage is adequate for a parameterless discovery tool.

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 takes zero parameters, so there is nothing for the description to disambiguate; baseline 4 applies. The description correctly avoids inventing filter or pagination parameters that the schema does not expose.

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?

States a specific verb ("Discover") and resource ("the SML Commit effect atlas"), then enumerates the contents: every registered action/target/owner/cap a commit check can authorize. It clearly distinguishes itself from the paid POST /v1/commit check, though it does not contrast itself against close siblings like commit_read_terms.

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 implies the use case (learn what a commit check can authorize without paying) and explicitly says the paid check is never invoked, which steers the agent toward this tool for pre-flight inspection. However, it never states when to prefer this over commit_read_terms or other commit-related siblings, leaving the alternative-selection decision implicit.

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