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

Given annotations already declare destructiveHint=true and openWorldHint=true, the description still adds substantial context the annotations cannot: every call creates a user-approved proposal before anything changes, creates land PAUSED, only 'execute' is a valid action, and there is one account per call with no fan-out. These are exactly the operational constraints an agent needs to avoid misuse.

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-loaded with the critical read/write distinction and the invocation form, then the constraints, then the categorized tool list. The 16-name enumeration is long but earns its place for routing; only marginal tightening is possible.

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, and the description compensates by covering the approval workflow, the paused-create behavior, the single-account limit, and how to resolve sub-tool argument schemas. For a router with nested arguments this is nearly complete; it could still note where proposal status is checked (list_pending_proposals/approve_proposal).

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%, so all three parameters are already documented and the baseline is 3. The description adds meaning beyond the schema by framing the call shape (action="execute", tool_name, arguments={...}) and by pointing to meta_ads(action="get_tool_schema") as the free way to discover the invoked sub-tool's argument schema, which is genuinely useful for a router.

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+resource: it is the write router for Meta Ads, carrying exactly the 16 tools that create/update/pause/remove. It explicitly names what it is not ('Reading, listing or checking anything is not here — that is meta_ads'), so an agent can distinguish it from the read router without opening either schema.

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?

Explicit when-to-use (any change to Meta Ads), when-not-to-use ('calling this router to look something up is always wrong'), and the alternative (meta_ads, plus meta_ads(action="get_tool_schema") for free schema lookup). Both the positive and negative paths are stated, not inferred.

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