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

Annotations already declare readOnly, idempotent, and non-destructive, so the safety profile is covered. The description adds genuinely useful behavioral context beyond that: these grants are 'explicit' and 'can be deleted directly,' and pool-derived access is out of scope — information an agent cannot derive from 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?

Two short sentences with no filler; the primary scope statement is front-loaded and the exclusion follows immediately. Every 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 read-only list tool with fully documented parameters, no output schema, and annotations carrying the safety profile, the description supplies the one thing the structured fields lack: the distinction between explicit and pool-derived grants. Return format and pagination are handled by the schema, so nothing critical 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?

Schema description coverage is 100% across all six parameters, including glob semantics, sort enum, cursor pagination, and ID patterns, so the schema does the heavy lifting. The description adds no parameter-level detail beyond what is already documented, which is the baseline 3 case.

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 states a specific verb and resource ('Lists explicit machine grants') and immediately scopes what is and isn't included by contrasting explicit grants with pool-derived access. It does not name a specific sibling tool, but the resource is unambiguous within the grant_machines_* family.

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 tells the agent the condition under which this list is the right one (explicit grants) and where the excluded case lives ('Pool-derived machine access is managed through project machine pool grants'), effectively routing the agent to the pool-grant tools. No explicit named alternative tool or prerequisites, so not a full 5.

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