threads_reply

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

Annotations cover the safety profile, but the description adds substantial context beyond them: required scopes, permission differences between own and others' root posts, ~30s processing latency, non-idempotency with a concrete recovery procedure, and a prompt-injection caution about other users' comments.

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?

Front-loaded with the action, then preconditions, ID sourcing, permissions, constraints, and retry guidance in a logical order. Slightly long and restates the character limit already in the schema, but nearly every sentence earns its place.

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 non-idempotent publish tool with three required parameters and no schema descriptions, the description covers authorization, ID provenance, constraints, latency, return value (post_id), and failure recovery. An output schema exists, yet the return mention is brief and not redundant.

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 carry the burden, and it does: it explains where account_id and reply_to_id come from, the semantic distinction between a comment id and a root post id, and that text is sent unchanged. The 500-char and non-blank constraints duplicate the schema slightly but add the 'sent unchanged' nuance.

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?

States a specific verb and resource ('Publish a text reply to a specific Threads post or comment') and is immediately distinguishable from siblings like threads_publish_text, threads_quote_post, and threads_repost by naming the reply target.

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?

Explicit preconditions ('only after the user explicitly approved the exact reply text, target, and account'), explicit ID sourcing (threads_list_accounts, threads_list_posts, threads_list_replies), and an explicit disambiguation rule: use the comment's id, not its root post's id.

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