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

Annotations already declare the safe-read profile (readOnlyHint, idempotentHint, destructiveHint=false), so the description needn't restate safety. It adds value beyond annotations by disclosing the return payload shape and the tier vocabulary (live|provisioning|planned), which is behavioral context the annotations cannot carry. It stops short of note on freshness/caching or the cost of enumerating the full roster, so not a 5.

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?

Front-loaded with the core action, then cleanly segmented into 'When to use', 'Do not use', and 'Returns'. Every clause earns its place, and the routing information is placed ahead of the return detail.

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 output schema, the description compensates by enumerating the returned fields and the tier enum values, and the sibling routing closes the main ambiguity (list-all vs single-chain status vs capabilities). For a zero-parameter read-only roster tool, nothing an agent needs is missing.

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 per the rubric the baseline is 4. There is nothing to document and no risk of an undocumented argument; the description correctly omits parameter talk.

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 and resource ('List every chain on the RobotBase roster with its state') and immediately scopes it against named siblings chain_status and robotbase_capabilities. An agent can distinguish this tool's job from every nearby roster/chain tool without opening a schema.

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 when-to-use triggers (which chains are supported, which nodes are online, where to start) and explicit do-not-use routing to two specific alternatives with their own conditions. Nothing is left to inference.

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