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

Annotations already mark the tool as read-only and non-destructive, and the description adds valuable behavioral context beyond that: it reveals the polling use-case, the exact thread-matching guarantee, the 10-second rate constraint, and cost/latency characteristics. This goes well beyond the structured 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?

The description is well-structured with a front-loaded purpose, concrete examples, explicit usage rules, and concise cost/latency notes. Every section earns its place and the length is appropriate for the tool's complexity.

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?

Despite having no output schema, the description tells the agent what the tool returns (state, messages, reply count), when to call it, how to identify the correct conversation, and operational constraints. An agent has enough information to select and invoke this tool correctly.

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%, so the schema already documents all three parameters. The description adds realistic example mappings and clarifies that reference requires business_number, but most of that is also present in the schema. It is acceptable but does not meaningfully expand on the structured parameter definitions.

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 ('Read'), a specific resource ('a two-way conversation thread you started'), and the exact content returned (state, every message, reply count). It clearly distinguishes this from generic status/outcome tools among the siblings by emphasizing the two-way thread and the business's replies.

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?

Provides explicit WHEN TO USE guidance: after send_message returns a conversation_id, poll this tool to read the business's reply. Also gives a clear WHEN NOT TO USE restriction (do not poll more often than every 10 seconds), and adds a safety guarantee that replies are matched to the exact thread. This is strong contextual routing for an agent.

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