List replies on a Threads post

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

Annotations already declare readOnlyHint=true and destructiveHint=false, covering safety. The description adds behavioral context beyond annotations: the conversation flag changes the scope from direct replies to the entire thread, and the ordering note about reply_to_thread implies a workflow dependency. This adds value beyond the structured fields.

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?

Two sentences with no filler. The main action is front-loaded, and the key caveat about conversation is stated clearly. Every word earns its place; it is highly concise and well-structured.

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 read-only list tool with 3 well-documented parameters, the description covers the essential usage, including the conversation flag and sequencing. It does not describe pagination or return format, but the schema covers limits, and no output schema exists, so the description is adequate. Slight gaps (e.g., no mention of error cases) are minor given the tool's simplicity.

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 (postId, limit, conversation). The description reiterates the conversation behavior (also in schema) and adds the 'Use before reply_to_thread' guidance, but that is not parameter semantics per se. Since the schema carries the full parameter documentation, the description adds little beyond it, warranting a baseline of 3.

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') and resource ('replies on a Threads post'), which is unambiguous and distinguishes it from siblings like list_threads_mentions or search_threads_keyword. The title reinforces this. It clearly tells the agent what the tool does.

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 contextual guidance: 'Use before reply_to_thread so you answer with the actual conversation in view.' This gives sequencing advice. It also explains the conversation flag's behavior ('true = the whole thread'). However, it does not explicitly state when NOT to use it or name alternative tools (other than the sequencing hint), so it lacks full when-not/alternatives coverage.

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