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

Annotations already mark destructiveHint trueessed, but the description adds critical behavioral context: 'Moves real money, so it always requires the human' and the outbound-tier approval card workflow (per-send rail, no standing grant, sends exactly once on approve). It also notes a 'structural cap applies,' giving a risk-relevant nuance beyond the annotations.

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?

The description is dense but well-structured: first sentence states purpose, second adds consequence and constraint, third gives usage timing, and the bracketed note contains the approval rail. Every sentence earns its place, though the bracket is protocol-heavy and could be condensed.

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 destructive, money-moving tool with no output schema, the description fully covers what the agent needs: what it does, units, cap, human-approval requirement, per-call approval card behavior, and when to invoke it. Nothing critical is missing for correct invocation.

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 the baseline is 3. The description adds only a redundant mention of 'account currency, major units' (already in the schema) and a vague 'structural cap applies,' which doesn't meaningfully clarify any parameter's format or constraints beyond the schema.

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 states a specific verb and resource: 'Change the daily budget of a Meta ad set.' It adds precision with unit details ('account currency, major units') and a cap constraint, making its scope unmistakable and distinguishing it from sibling tools like update_x_ad_budget or set_meta_ad_status.

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 when to use: 'Use when the user explicitly asks to raise or lower spend on a campaign.' It also gives operational timing with 'Call it on the first clear ask' and clarifies that the approval card is the confirmation, so the agent knows not to re-ask. This is unusually actionable.

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