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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, so safety behavior is covered by structured data. The description adds the returned fields and the conversion-optimization context, but doesn't describe pagination, filtering, or rate limits.

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 tightly packed sentences that front-load the resource and fields, then immediately follow with the actionable routing context (OFFSITE_CONVERSIONS optimization). No waste.

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?

With an output schema present, the description needn't explain return values, and it correctly focuses on scope and purpose. It's complete for a simple one-param list tool, though it could mention that results may be paginated or require an active Meta connection.

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?

Only one parameter (account_id) with 0% schema description coverage, but the schema name is self-explanatory and the description clarifies that it scopes to a Meta ad account. No additional syntax or format details are provided, so baseline 3 is appropriate.

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 ('Lists') and resource ('conversion pixels in a Meta ad account'), and names the returned fields (id, name, last fired). It also distinguishes itself from sibling pixel-list tools (list_tiktok_pixels, list_tiktok_bc_pixels) by scoping to Meta.

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 the downstream use case: obtaining the pixel_id for ad sets optimizing OFFSITE_CONVERSIONS. It doesn't name alternative tools for pixel retrieval or when not to call it, so it falls short of a 5.

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