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

With no annotations provided (neither readOnlyHint nor destructiveHint), the description carries the full burden of behavioral disclosure — and it delivers well. It reveals determinism ('Deterministic'), return structure ('returns findings (masked), counts, and a redacted copy'), and critical cost implications ('Costs $0.005 per call'). This is strong disclosure for a state-free analysis tool, though it leaves some behaviors (latency, error handling on failed payment) undisclosed, preventing a 5.

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 tightly-packed sentences deliver maximum value. The first verb-to-the-point sentence states the purpose and exhaustive detector list; the second covers behavior, returns, and cost. The lengthy parenthetical list of secret types earns its place — it's the primary value proposition allowing the agent to verify coverage for its specific secret type. The 'Use before...' and cost details are efficiently integrated without fluff.

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 no output schema and no annotations to rely on, the description covers the essential dimensions: what it detects, how it behaves, what it returns, when to use it, and what it costs. The schema's api_key parameter description nicely complements by covering authentication and funding flows. Minor gaps remain (error handling, rate limits, idempotency semantics), but for a text-scanning tool this is well-covered. The priced nature of the tool is appropriately surfaced since it's the highest-stakes contextual fact.

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?

With schema description coverage at 50% (api_key is documented, text is not), the parameter burden is partially on the description. The description implicitly defines the text parameter by explaining what gets detected/redacted and the output shape, but never explicitly documents the 'text' parameter's constraints (though maxLength 100000 is in the schema). The api_key parameter itself is well-documented in the schema with funding details. The description adds moderate value by connecting tool behavior to parameter purpose, but doesn't fully compensate for the undocumented text parameter — a solid 3 meeting baseline expectations.

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 a specific verb+resource+scope: 'Detect & redact PII and secrets in text' followed by a comprehensive, concrete enumeration of detector types (private_key, jwt, aws_access_key, email, ssn, iban, etc.). This scope is clearly distinct from sibling tools that handle names (screen_name), crypto addresses (screen_crypto_address), and entity resolution (resolve_lei), making differentiation immediate.

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 description provides clear contextual usage guidance: 'Use before logging/forwarding untrusted or agent-generated text.' This tells the agent when the tool is appropriate. However, it stops short of explicitly naming alternatives or providing when-not-to-use exclusions — it doesn't compare against siblings or describe conditions under which this tool would be the wrong choice, which is why it doesn't reach a 5.

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