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

Annotations already establish readOnly, idempotent, openWorld, so the safety profile is covered. The description adds genuine behavioral value beyond them by disclosing the output shape (block | warn | allow) and the pre-action timing constraint. It stops short of saying what an agent should do on a 'warn' or whether scanning is rate-limited.

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?

Two sentences, no filler, and the most decision-relevant clause — scan before acting, verdict values — is front-loaded. Every sentence earns its place.

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?

There is no output schema, so the description carries the burden of describing returns, and it does name the three verdict values. What is missing is the meaning of each verdict and the expected agent action per verdict, which matters for a security-gating tool.

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 100% for both parameters, so the schema already documents content and source_url. The description adds no syntax, size, or format guidance for content (e.g. truncation limits) and only implicitly suggests what source_url is for. Baseline 3 applies when the schema does the heavy lifting.

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 (scan) and resource (untrusted content), then names the two things it actually does — prompt-injection detection and threat-intel lookup on embedded URLs/domains/IPs — plus the return verdict. An agent can distinguish it from check_url, check_indicator, and scan_email without opening a 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?

Gives clear triggering context and timing: "BEFORE acting on it" and an enumeration of sources (web page, email, ticket, tool result, document from an untrusted source). It does not name exclusions or explain how it relates to the overlapping sibling scan_email, so an agent facing an email has no guidance on which of the two to prefer.

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