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

Beyond the annotations (destructive/openWorld/non-idempotent), the description discloses the real-world effect ("puts a post on real accounts"), that per-platform validation happens inside this call, and the failure contract: on mismatch the draft stays a draft and the reasons are returned. That failure semantics is exactly the information annotations cannot carry.

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?

Four compact sentences, front-loaded with the action and mode split, then the safety condition, then failure behavior, then discovery. Slightly dense and parenthetical-heavy, but no sentence is expendable.

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?

With no output schema, the description still specifies what comes back on the failure path (reasons per platform) and how to locate the required `task_id`. For a destructive 4-parameter tool, nothing an agent needs to call it correctly is missing.

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 baseline is 3, but the description adds a genuine constraint the schema does not enforce: "Exactly one of the two" for `publish_now` vs. `scheduled_at`. Minor deduction because timezone's role is left entirely to the schema.

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 ("Sends a DRAFT") plus the two mutually exclusive modes (scheduled vs. immediate). It distinguishes itself from create_post (which only saves the draft) and from update_post, so an agent can tell it apart from siblings without opening schemas.

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 precondition: only call when the user has said to send that draft and when. It also routes to alternatives — create_post `save_as_draft` to produce the draft and list_posts status DRAFT to find it — covering both the before and after of this tool's place in the workflow.

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