Publish or schedule a post

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

Goes well beyond the annotations: discloses 500-character auto-threading, the 30-minute boundary that selects between publish-now and schedule permissions, the possibility of blocking on owner confirmation when the connection is set to "ask", and idempotency_key retry behavior. The idempotentHint=false annotation is not contradicted — the description explains how to opt into idempotency per-request rather than claiming the tool is idempotent by default.

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 and mode, then media shapes, then threading, then the permission/confirmation model, then the usage trigger. Five dense sentences with no filler; the long permission sentence carries information an agent cannot get from the schema.

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 7-parameter open-world mutation with no output schema, it covers modes, media, permissions, approval gating, and retry safety. It stops short of describing what comes back (post id, scheduled job id) or what happens on validation failure, which matters given there is no output schema to lean on.

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 coverage is 100% so the baseline is 3, but the description adds real semantics: media_urls count maps to image vs carousel (2–10), video_url is the mutually exclusive alternative, publish_at is "ISO 8601 with offset", and publish_now versus publish_at is an either/or. Only account_id and idempotency_key remain thin.

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 (publishes) and resource (a post to Threads) plus the two modes (now via publish_now, later via publish_at). It does not explicitly name the sibling `schedule_text`, which is the nearest-looking alternative, so an agent must infer the boundary from the "final text" phrasing.

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?

"Applies when the user has final text and wants it on Threads" gives a clear triggering condition and implicitly rules out draft/generation flows (generate_posts, build_material). No explicit exclusion versus `schedule_text` or pointer to `cancel_schedule`/`list_schedules` for the inverse operation, so the routing guidance is clear but not complete.

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