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

Annotations already declare mutation semantics (readOnlyHint=false, openWorldHint=true), but the description adds genuinely non-derivable behavior: a per-call price of $0.01 USDC via x402, a hard cap of 20 targets, and the security-relevant guarantee that credentials are used once and never persisted. It stops short of describing failure/partial-success behavior, which matters for a multi-target publish.

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 sentences with no filler, and the cost/target-limit constraint is front-loaded before the capability list. The parenthetical auth details compress a lot into little space without becoming unreadable.

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 two-parameter, no-output-schema tool, the description covers cost model, target ceiling, supported destinations, credential handling, and the payment handshake, which is close to sufficient. The remaining gap is what a caller gets back across many targets (partial failures, per-target results), which an agent would reasonably want before invoking.

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 description coverage is 100% and the jobs parameter already spells out the per-target object shapes, so the schema is doing the heavy lifting. The description adds no further detail about the jobs array structure, target mix, or ordering, 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?

The description uses a specific verb ("Publishes") and enumerates the concrete destinations and auth mechanisms (Discord webhook, Telegram bot, Bluesky app password, generic webhook), so the agent knows exactly what the tool does. It does not, however, contrast itself with the sibling omnipost_fanout, which appears to be the closest alternative for multi-target delivery.

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?

Usage is only implied: the pricing line and the "credentials used once and never stored" remark suggest this is the go-to direct-publish path, but there is no explicit when-to-use/when-not guidance and no routing to omnipost_fanout or omnipost_validate. The one actionable hint (omit payment_signature to receive the challenge) is largely duplicated by the schema.

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