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

Annotations already signal mutating/destructive behavior (readOnlyHint false, destructiveHint true), and the description adds substantial behavioral detail beyond that: the 365-day lookahead cap, upfront validation instead of late failure, the multi-brand refusal error, the returned payload shape (id, handle, brand), and cancelability. This is exactly the kind of risk-relevant context that helps an agent use the tool correctly.

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 dense sentences, each carrying distinct operational information: core action, preconditions/validation, edge case behavior, and return value plus cancellation. No filler or redundancy, and the most important scheduling distinction is front-loaded.

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?

Given 10 parameters, nested objects, and no output schema, this description covers the crucial gaps: what the return value looks like, how errors manifest, what must be verified before calling, and how to undo the action. Combined with the already-detailed schema, an agent has everything needed to invoke schedule_post correctly and interpret its results.

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 schema has 100% description coverage with rich parameter details, so the baseline is 3. The description adds meaningful value on top by specifying the run_at maximum horizon ('up to 365 days ahead') and by explaining the brand_id omission behavior across multiple brands, which the schema does not fully convey. It doesn't need to repeat parameter definitions already in 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?

The description opens with a specific verb and resource: 'Queues a post to be published publicly at a future time', which clearly separates it from immediate publishing and from cancellation. It emphasizes future scheduling as the core differentiator against siblings like post_to_social and cancel_scheduled_post, so an agent can immediately recognize its role.

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?

It clearly implies scheduling for future publishing versus immediate publishing, and it lists key conditions for safe use: connected platforms, per-platform media suitability, and the brand ambiguity rule. It doesn't explicitly name 'use post_to_social to publish now', but the future-time framing and connection/refusal guidance give strong contextual direction.

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