Update Meta Pixel

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

The description adds no behavioral context beyond what the annotations already provide. It does not clarify whether this performs a partial update (leaving unspecified fields unchanged) or a full replacement, nor does it describe any side effects or requirements. Annotations already indicate idempotentHint and destructiveHint, so the description contributes nothing new, though it does not contradict any 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 concise: a one-sentence summary followed by an args list. The information is front-loaded and easy to scan. The args list is detailed but not excessively long for a tool with six parameters. It avoids unnecessary fluff and is well-structured for quick parsing.

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 relatively simple, and the description covers most parameters. However, it lacks crucial context about update semantics (partial vs. full) and does not mention error conditions or prerequisites (e.g., pixel must exist). Since there is no output schema, the description could also explain what the response contains, but it does not. The description is adequate but leaves notable gaps.

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?

The description lists all parameters except response_format, and provides partial enum values and an example for automatic_matching_fields. This is valuable because schema coverage is only 17%, leaving most parameters without descriptions. However, it omits response_format entirely, which has a schema description, and it does not explain the meaning of fields like automatic_matching_fields—only provides an example. It is helpful but not comprehensive.

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 'Updates pixel settings' which is a clear verb (Updates) and resource (pixel settings). It is specific enough to distinguish from create/get/delete siblings, but does not explicitly name alternatives. For an agent, the verb 'updates' implies modification of an existing pixel, which is unambiguous.

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 provides no guidance on when to use this tool versus alternatives. It does not mention that this is for modifying existing pixel settings, nor any prerequisites like the pixel must exist. No alternative tools are referenced, and no conditions for use vs. non-use are given. The agent must infer usage solely from the tool name.

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