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 genuinely new behavioral context beyond that: 'Works without a key,' which tells an unauthenticated agent it can still bootstrap. It does not say what an omitted section returns, which keeps it short of 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?

Two sentences, front-loaded with what the manual is, then the navigational index. The topic list in sentence one and the section list in sentence two overlap slightly (send/states/errors/approvals/policies/agents/inbox/ocr appear twice), a minor redundancy rather than bloat.

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-value detail is not required, and a one-optional-parameter read-only tool needs little else. The only missing piece is default behavior when no section is passed; everything an agent needs to invoke it correctly is present.

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 coverage is 0% and the single 'section' parameter has no enum, so the description carries the full burden — and it does, listing the exact nine valid values (overview, send, states, errors, approvals, policies, agents, inbox, ocr). It does not state the behavior when section is omitted (default null), leaving one small gap.

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 the resource plainly ('The manual for Fax for Agents') and enumerates the topics it covers, so an agent can tell it apart from every operational sibling (send_fax, get_fax_status, etc.) at a glance. It never uses an explicit verb like 'returns' or 'reads', but the intent is unambiguous.

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 section list hints that an agent should consult the 'errors' section when debugging or 'send' before composing a fax, but nothing says when to call this versus the operational tools, or that it should be read before first use. No exclusions or alternatives are named.

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