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

Annotations already declare readOnly, idempotent, non-destructive. The description adds genuinely new behavior: results are newest-first, pagination continues via cursor, and the required OAuth scope is fax:read. It stops short of stating page-size behavior or result cardinality.

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 tight sentence that front-loads what is listed, then ordering, then the optional filter, pagination, and scope. No wasted words.

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. For a simple read/list tool the description covers scope, ordering, filtering, and pagination adequately; only the 'limit' parameter and valid state values are left unaddressed.

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%, so the description carries the burden. It explains 'state' as an optional filter and 'cursor' as pagination, but never mentions 'limit' (default 20) or any valid state values, leaving one of three parameters unexplained.

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 ('Sent faxes of your organization'), plus ordering and an optional filter. 'Sent' implicitly separates it from inbound siblings like list_inbox and read_inbound_fax, though no sibling is named 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?

Usage is only implied: describing the listing scope and the optional state filter suggests when to reach for it, but there is no explicit 'use this when' or routing to alternatives such as list_inbox for inbound messages.

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