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

With annotations already indicating readOnlyHint=true and openWorldHint=false, the description adds meaningful behavioral context: the cost implication ('Costs zero credits'), the relationship to screen_address (fresh vs. historical), and the specific output fields ('reputation score, band, confidence, sanctioned flag, and top evidence signals'). This goes beyond the annotations without contradicting them.

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?

The description is three sentences, each packed with distinct value: purpose/scope, use case, and key differentiator with alternatives. It is front-loaded with the essential action and avoids redundancy.

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?

For a relatively simple read-only tool with full schema coverage and an output schema present, the description provides complete context: what it returns, how it compares to a sibling, and when to use it. Nothing essential is missing.

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 input schema already provides full coverage for both parameters (address and limit) with detailed descriptions, including format and constraints. The description does not add parameter-specific semantics beyond what the schema offers, so the baseline of 3 is appropriate.

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 the verb-resource pair: 'Retrieve the authenticated user's prior screening runs for a specific Ethereum address.' It explicitly distinguishes from siblings by naming get_screening_history for all addresses and screen_address for fresh runs.

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?

Provides explicit when-to-use guidance: 'Use it to recall context for an already-screened address.' It also gives an exclusion criterion: 'Costs zero credits, unlike screen_address which always runs a fresh screen,' and points to the alternative get_screening_history for broader queries.

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