reply_to_thread

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

Annotations indicate the tool is mutable but not destructive. The description adds one behavioral detail (auto-resolution of channel) which is useful. However, it does not disclose potential side effects like notifications or permissions, and annotations already cover the safety profile.

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 extremely concise with two sentences, no fluff. The key information is front-loaded: the purpose and a crucial parameter hint.

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 tool with low complexity (3 params, no nested objects, output schema exists), the description is adequate but minimal. It covers the essential purpose and one parameter behavior, but could mention thread context or output expectations.

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 must compensate. It only explains the 'channel' parameter's auto-resolution. The 'text' and 'thread_id' parameters are left without explanation. Given the low coverage, the description adds minimal semantic value.

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 clearly states the tool's action ('Reply') and resource ('into a thread'). It distinguishes from sibling tools like 'send_message' by focusing on thread replies and mentions auto-resolution of channel.

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?

The description provides a useful hint about channel auto-resolution but does not explicitly guide when to use this tool over alternatives like 'send_message' or 'get_thread_messages'. With 27 siblings, more explicit guidance would be beneficial.

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