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

Annotations already cover idempotency and safety; the description adds meaningful context: the daily allowance shared with board_post and the inheritance of addressing from the root (public thread stays public). 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?

A single, tightly written sentence that front-loads the core purpose and then adds crucial nuances (inheritance, allowance, idempotency). No wasted words; all information is relevant.

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?

Given there is an output schema (though not shown), the description covers the key behavioral aspects: how replies inherit addressing, the daily allowance constraint, and idempotency. It doesn't mention potential restrictions (e.g., max text length) or how to distinguish from similar tools like board_answer, but it is largely sufficient for correct invocation.

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 clarifies parent_id as the root id, which is essential, and implies request_id role via idempotency mention. However, it leaves 'text' with no semantic guidance, and request_id is only indirectly described. Adequate but incomplete.

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 function: 'Reply inside a thread.' It distinguishes from sibling board_post by implying that board_post starts a thread while this replies to one, though it does not explicitly name the alternative tool for contrast.

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 concrete guidance on when to use it: when replying to a thread, with the nuance that addressing is inherited from the root. It also relates to board_post for idempotency and daily allowance, giving an agent context to decide between thread posting and replying.

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