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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description adds genuine behavioral context beyond that: the servability dimension (is_servable, reasons_not_servable) signals some instruments may be unusable, and the currency/credit-limit fields hint at account-context dependency. It says nothing about auth or rate limits, but the added semantics are real.

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?

Content is front-loaded with the resource and its fields, then the downstream dependency, then a docs link. Every element is informative, though the exhaustive field listing partially duplicates the output schema.

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?

The tool is simple (one optional param, output schema present) and the description covers what it returns and why it matters in the drafting workflow. It is complete enough to invoke correctly; only the absence of any non-servable/pagination handling note keeps it from a 5.

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?

With a single parameter at 100% schema description coverage, the schema already documents ad_account_id including the empty-string fallback to reddit.ad_account_id in config. The description adds nothing parameter-specific, 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 names the specific resource (funding instruments/billing and posting profiles of a Reddit ad account) and enumerates the returned fields, so an agent knows exactly what it fetches. The verb is implicit ('Returns ...'), but combined with the list_ prefix the purpose is unambiguous and distinguishable from siblings like get_reddit_campaigns.

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 explicitly routes the agent: draft_reddit_campaign needs a servable funding_instrument_id and draft_reddit_ad needs the profile_id, and states both come from this tool. That is clear when-to-use context, though it stops short of any when-not-to-use or exclusion guidance.

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