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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false, and closed-world, so the safety profile is covered. The description adds genuinely non-redundant behavior: no account or key is required, and every record is synthetic and marked as such — important context for a demo tool whose output could otherwise be mistaken for real data.

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?

Three short lines, front-loaded with the payload contents before the no-auth note and the call-order instruction. Every sentence carries distinct information and none is padding.

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?

An output schema exists, so the description need not enumerate return fields, and it still summarizes the sample contents at a glance. Combined with the no-key note and the next-step routing to signup_free, an agent has everything needed to call this 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?

The tool takes zero parameters, so the baseline is 4 and there is no syntax or format meaning for the description to add. Nothing here is missing or misleading on the parameter front.

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 exactly what the tool returns — a labeled sample consisting of a pixel, a consent receipt, and two contacts — and the title 'See sample output' supplies the action. An agent can distinguish this preview tool from siblings like signup_free, create_pixel, or get_contacts without opening any schema.

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?

It gives explicit sequencing: 'Call this first to show the person what AgentPixel returns, then call signup_free.' That names both the condition for using this tool and the follow-up alternative, leaving nothing to inference.

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