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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered; the description reinforces it with 'WITHOUT creating any posts' and enumerates the validation dimensions, which is genuine added context. It stops short of describing what a failed validation yields (errors vs. warnings), which a dry-run tool would benefit from.

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 short sentences, zero filler, with the non-mutating guarantee and the ordering prerequisite front-loaded. Every clause 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 pure validation tool the description covers intent, scope, and sequencing, and the nested schema is rich. The only meaningful gap is that no output schema exists and the description never indicates what validation returns (pass/fail shape, error list), which is the tool's entire product.

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% and the single nested 'schedule' parameter is documented in detail in the schema itself (minimal shape, campaign variant, per-post settings like tiktokPostMode). The description only refers to 'a schedule document,' adding no meaning beyond the schema, so the baseline 3 applies.

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?

Specific verb (validate) plus the exact resource (schedule document) and the full scope of checks (provider rules, media limits, account state, publish times). 'WITHOUT creating any posts' cleanly separates it from apply_schedule, so an agent can distinguish it from siblings without reading 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?

Explicitly states the usage rule: 'Always run this before apply_schedule.' That is both a when-to-use directive and a dependency on a named sibling, leaving nothing to inference.

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