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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds real value on top: default ordering (newest first), the metadata-only payload shape, and the required permission scope 'inbox:read' — a genuine behavioral disclosure an agent needs before calling.

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?

A single terse sentence with the payload shape front-loaded and the permission scope trailing; every clause earns its place and there is no padding.

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?

The output schema exists, so return values need no explanation, and the description covers ordering and payload scope. However, for a paginated list tool with two undocumented parameters, the absence of any limit/cursor semantics leaves a real gap an agent must fill by guessing.

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%: neither 'limit' nor 'cursor' is documented anywhere. The description does not mention either parameter, how pagination works, or whether 'newest first' interacts with cursor direction — the one piece of semantics the description could have supplied but did not.

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 resource and scope: received faxes, ordered newest first, metadata only (sender header, pages, status). The 'metadata only' qualifier implicitly separates it from read_inbound_fax, which retrieves content, though it never names that sibling explicitly.

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?

There is no explicit guidance on when to choose this over read_inbound_fax or list_faxes; usage is only implied by the 'metadata only' phrase and the tool name. An agent can infer the boundary with the content-reading sibling, but nothing states it, and no exclusions or prerequisites are given.

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