meta_ads_analysis_cost

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

With no annotations, the description carries the full burden and it does well: it declares the operation as read-only and describes the output (decomposition with per-driver magnitude and action hint). It does not go into quota/cost limitations or auth details, but that is not critical for an analysis tool.

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 concise and front-loaded: the first sentence states the core purpose, and the second gives the primary use case. Every sentence adds value, and the list of drivers is informative without being verbose.

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 diagnostic tool with no output schema, the description provides a solid overview of what the tool returns (driver decomposition, magnitude, action hint). It could be slightly more explicit about the exact return structure or data scope, but overall it is sufficient for an agent to select and invoke the tool correctly.

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%, so the schema already documents all three parameters thoroughly. The description adds no additional parameter-level meaning, which is acceptable because the schema descriptions are detailed (period ranges, account_id format with fallback).

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 ('diagnoses') and clearly identifies the resource (Meta Ads campaign cost/CPA issues). It enumerates the specific drivers it attributes cost changes to, which distinguishes it from sibling analysis tools like meta_ads_analysis_performance or google_ads_cost_increase_investigate.

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?

The description gives an explicit use case: 'Use this when the operator reports why did CPA jump'. It also clarifies what the tool does—separating auction-side from creative-side causes—but does not explicitly state when not to use it or name alternative tools.

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