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

Annotations already declare destructiveHint=true and readOnlyHint=false, covering the mutation nature. The description adds that it modifies 'multiple' records and happens 'in one request', which is extra context beyond annotations. No contradiction; it reinforces safety expectations but adds little beyond scale.

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 sentences, no filler. The primary action and scope are front-loaded, and the side-effect note is brief. Every word 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 bulk update with a nested payload and an output schema present, the description covers the core action and scale. It doesn't mention error handling or prerequisites, but those are not required for a straightforward mutation tool. It is sufficiently complete.

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%: both parameters are described inline. The description repeats the 'is_read and/or comment' fields but adds no new syntax, constraints, or usage nuance. Baseline 3 is appropriate since schema does the heavy lifting.

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 ('Update') and resource ('multiple fax records') and lists the exact fields ('is_read and/or comment'). It clearly differentiates from siblings like bulk-delete-faxes (delete vs update) and bulk-update-outbox-faxes (outbox vs general faxes) without needing the 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?

The description implies use for updating multiple faxes but does not explicitly contrast with single-record update-fax or the outbox variant. It lacks explicit 'when to use this vs that' guidance, though the context is reasonably clear.

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