update_custom_pixel

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

With no annotations, the description must bear the full burden of behavioral disclosure, but it provides none. It doesn't mention idempotency, partial vs. full replacement, required permissions, error behavior, or any side effects. This is essentially a restatement of the tool name with no added transparency.

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 a single, concise sentence that immediately states the tool's purpose. No wasted words or fluff, front-loaded and appropriately sized for a simple CRUD operation.

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?

Despite having a complete schema, the description is too sparse for the tool's context. It doesn't explain the relationship to update_pixel, the significance of the 'events' or 'source' fields, or any operational constraints. With no annotations or output schema, the description leaves the agent with little guidance beyond the raw schema.

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 input schema covers all 5 parameters with descriptions (100% coverage), so the description need not repeat them. However, the description itself adds no parameter-related context beyond what's in the schema, meeting the baseline for complete schema coverage.

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 the action ('Update') and resource ('custom pixel'), and the word 'existing' implies the tool modifies an already-created pixel, distinguishing it from create_custom_pixel. However, it doesn't explicitly differentiate from the sibling update_pixel, so it lacks full sibling differentiation.

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 phrase 'existing custom pixel' implies use when modifying an existing pixel rather than creating one, but there is no explicit guidance on when to use this tool versus alternatives like update_pixel or create_custom_pixel. No exclusions or alternative references are provided.

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