failed_units

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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the description's 'Read-only' statement is redundant with structured data and earns no credit. It does add one piece of behavioral context — that the tool is scoped to a single manager's failed units — which is modest value beyond the annotations.

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?

Three short sentences, front-loaded with the purpose, then the safety trait, then the parameter constraint. Only 'Read-only' is arguably wasted since annotations already state it.

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?

An output schema exists, so return values need not be described, and the one required parameter's values are given. The main remaining gap is that 'manager' is never defined and no sibling routing is offered, but for a single-parameter read tool this is close to sufficient.

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?

Schema description coverage is 0% and the sole parameter has no enum in the schema, so the description carries the full burden; it does so by spelling out the allowed values 'user' or 'system'. That is exactly the information an agent needs to call the tool, though it omits the default and what each value selects.

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 the failed units') and narrows scope ('of one manager'), which distinguishes it from the sibling list_units that presumably returns all units. It does not explicitly name or contrast against list_units or the other siblings, so it falls short of a 5.

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?

Usage is only implied: the agent can infer this is for diagnosing failed services rather than listing everything, but the description never says when to prefer failed_units over list_units or unit_status. No alternatives or preconditions are named.

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