threads_get_replies

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It clearly states that the tool returns only direct replies, specifies the return format as a JSON string with id, text, timestamp, and username, and mentions the default limit. This is sufficient behavioral context for a straightforward fetch operation.

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 and appropriately sized: a purpose statement, a clarifying sentence about single-level replies, an Args section, and a Returns section. It is front-loaded with the essential purpose, and every sentence earns its place without waste.

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 the absence of annotations, the description covers the critical aspects for a simple fetch tool: what it does, what parameters it takes, and what it returns. The inclusion of the return structure and the limitation to direct replies provides a complete enough picture for the tool's complexity.

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?

The input schema has no descriptions for parameters (0% coverage), so the description must compensate. It does by explicitly explaining post_id as the ID of the post, and limit as the maximum number of replies with a default of 25. This adds meaningful semantics beyond the raw schema and fully clarifies each parameter's purpose.

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 uses a specific verb 'Fetch' with the resource 'direct replies to a specific Threads post'. It also distinguishes itself from siblings by clarifying it returns only single-level direct replies, not recursive thread reconstruction, making the purpose unambiguous.

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 clear context by specifying the scope: only single-level direct replies. It explicitly states what it does NOT do ('not recursive thread reconstruction'), which serves as a when-not guideline. However, it does not name alternative tools for that use case, so it stops short of complete alternative guidance.

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