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

Annotations already declare readOnly/non-destructive, and the description adds substantial context above that bar: the shape of the `error`/`reason` object with code, message, action and retryable, plus the `accountHold` condition and the counterintuitive rule that a past-due "pending" entry is held rather than stuck. That last point prevents a real misdiagnosis an agent would otherwise make.

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-loads the core action, then layers failure semantics and the accountHold edge case in descending order of importance. Four sentences, none redundant, and the deferred-sibling pointer sits at the end where it belongs.

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?

No output schema exists, so the description must describe the return payload — and it does: per-platform entries, error/reason fields, and the accountHold flag. Combined with the trivial one-parameter schema, an agent has everything needed to call and interpret it.

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?

Only one optional parameter (`limit`) with 100% schema description coverage, so the schema fully carries its meaning and the description adds nothing about default, max, or pagination behavior. Baseline 3 is appropriate when the schema does the work.

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 ("Get the user's recent post history") plus the distinctive scope: per-platform success/failure tracking. It implicitly separates history from scheduling by deferring scheduled items to get_scheduled_posts, but never frames that as an explicit contrast, so the sibling differentiation is only partial.

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?

"Useful for checking what was posted and what failed" supplies a clear use case, and the closing sentence points at get_scheduled_posts for the adjacent question of which posts are held. No explicit when-not or full routing statement, so it stops short of a 5.

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