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

Goes beyond the readOnlyHint/openWorldHint/destructiveHint annotations by disclosing the return shape (labeled placeholders), the guarantee that original text is never returned, and a billing note that each call consumes one Request on the plan. Missing only edge-case behavior such as input size limits or what happens when no PII is found.

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?

Front-loaded with the action and output contract, then a clearly separated usage paragraph; no filler sentences. The placeholder examples are slightly repetitive but earn their place by making the output format concrete.

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?

The tool is simple (one required string parameter) and an output schema exists, so return values needn't be spelled out — yet the description still summarizes them usefully along with the quota cost. Nearly complete; only input limits and no-PII-match behavior are left unstated.

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?

Only one parameter, and the schema already describes it fully at 100% coverage ('The text content to redact PII from'). The description adds no syntax, encoding, or size guidance for that parameter, so the schema carries the whole burden — baseline 3.

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 ('Redact PII ... from text') and enumerates the entity classes it targets, plus the exact output form ([EMAIL_REDACTED], etc.). It implicitly separates itself from promptguard_scan_text by asserting 'Never returns the original text', but never names the scan sibling or contrasts the two explicitly.

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?

A dedicated 'When to use' clause gives three concrete scenarios (pre-LLM prompt, customer messages, RAG ingestion), which is clear context for selection. It stops short of stating when not to use it or pointing to promptguard_scan_text for detection-only needs.

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