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

Adds real context beyond the annotations: the $1 charge, the batch and payload caps, the session-verification prerequisite, and the important caveat that results are heuristic indicators rather than calibrated probabilities or a safety guarantee. It also clarifies no model calls or automatic follow-on purchase occur. It does not explain why readOnlyHint is false for what reads like a screening operation (presumably billing/session state).

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?

Compact and front-loaded with the batch scope, but it opens with a bare '$1' and uses opaque jargon ('checkout caller', 'verified fixed-order session') that forces the agent to guess at meaning. No sentence is pure filler, but several are cryptic rather than economical.

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 return values need not be described, and the cost/caps/caveats cover most operational concerns. What remains missing is the meaning of agent_id and the required/optional status of session_id — material gaps for a tool whose call will fail if those are supplied wrongly.

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?

Schema description coverage is 0% across three parameters, so the description must carry the load. It partially documents 'texts' (1–20 samples, 64 KiB total cap) but says nothing about agent_id, and only obliquely gestures at session_id via 'verified fixed-order session' without stating whether it is required or optional.

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 and resource: screening a batch of 1–20 text samples for 'deterministic injection markers'. An agent can tell this is text-content screening rather than source scanning, though the description never names scan_source or security_preflight to make the boundary explicit.

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 supplies hard preconditions (Direct MCP requires the checkout caller and a verified fixed-order session, max 64 KiB total, 1–20 samples) but gives no explicit when-to-use vs. when-not guidance relative to the sibling tools like scan_source or security_preflight. Usage is implied by the constraints rather than stated as routing advice.

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