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

Annotations already carry readOnly, idempotent, and non-destructive hints. The description adds useful behavioral context beyond that: the read does not claim inbox work, access is restricted by mailbox policy and blocks, and pending tasks have no response yet. No contradiction with 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?

Four short sentences, each carrying distinct information: operation, scope, access constraint, parameter source, and a behavioral note about pending tasks. Nothing is redundant.

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 simple one-parameter read tool with a full output schema and safety annotations, the description covers everything an agent needs: what it reads, authorization limits, side-effect-free behavior, and the no-response-yet edge case. No important gap remains.

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 100%, and the description essentially repeats the schema's task_id provenance ('returned by send or inbox collection') rather than adding new parameter meaning. This is the expected baseline when the schema fully documents the only parameter.

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 opens with a specific verb and resource ('Read an existing task and its completed reply') and immediately differentiates from work-claiming siblings by noting it does not claim inbox work. This makes the tool's purpose unambiguous even without inspecting 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?

It provides clear context: when to use the tool, prerequisites (task ID from send or inbox collection), and access constraints (only requester/responder, subject to policy/blocks). It does not explicitly name sibling tools or state exclusions, so it stops short of a 5.

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