pixels_send_capi_event

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

With no annotations provided, the description carries full behavioral burden. It discloses a key behavioral trait: PII fields are auto-hashed with SHA-256 before sending, adding 'Meta requires this' for rationale. This is valuable transparency beyond what the schema shows. However, it does not mention response format, error handling, 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?

The description is concise and front-loaded with the purpose. The 'Args:' section is structured and provides examples without excessive verbosity. It earns its place, though the Args list could be considered redundant with the schema, but the examples add value.

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 tool with 18 parameters and no output schema, the description is incomplete. It omits required parameters like pixel_id (though schema marks it required) and many optional but important ones (fbc, fbp, user details, client IP, user agent). It does not explain return values or error conditions. The description covers only 5 of 18 parameters, leaving a significant gap.

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 adds meaning to several parameters (event_name, action_source with enumerated values, custom_data with a concrete example, event_id and test_event_code with usage context). However, schema description coverage is 0% and 18 parameters exist; many are completely undiscussed, such as pixel_id (required), fbc/fbp, user fields, event_time, client_ip_address, and client_user_agent. Partial compensation, not sufficient for the breadth.

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 clearly states 'Send a server-side conversion event via Conversions API' with a specific verb and resource. It distinguishes itself from sibling tools like pixels_create and pixels_get, which handle other pixel operations. This 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 implies usage for server-side event tracking but does not explicitly compare with alternative tools or state when not to use it. It provides some contextual guidance, such as 'event_id' for deduplication against client-side events and 'test_event_code' for development, but lacks a clear 'use when... vs. when not...' directive.

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