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

Annotations already declare readOnlyHint=true and idempotentHint=true, but the description adds valuable behavioral context: default SLIM response with 240-char truncation, the include='full' parameter to override, rate limits ('Free: 30/hr, Pro: 500/hr'), and the exact return shape including next_calls. This goes well beyond what annotations convey and does not contradict 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?

Three sentences with no waste. The first sentence states the core purpose, the second adds the key behavioral detail (slim vs. full) and use case, and the third covers pricing, return structure, and sibling differentiation. 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?

Given full schema coverage, clear read-only/idempotent annotations, an output schema, and a description that covers default behavior, rate limits, return fields, and an alternative tool, the description fully equips an agent to select and invoke this tool without unresolved ambiguity.

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 has 100% coverage with all four parameters documented in detail (e.g., 'Substring match... Min 2 chars', 'format AML.T####'). The description echoes these concepts at a high level ('by keyword or referenced technique') but adds no parameter-specific meaning that isn't already in the schema.

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 tool's function: 'Search ATLAS case studies (real-world AI/ML attack incidents) by keyword or referenced technique.' It distinguishes itself from the sibling atlas_case_study_lookup by explicitly saying 'Drill via atlas_case_study_lookup for the full procedure list,' and gives a specific use case: 'Useful when the user has a technique in hand and wants to see incidents that exercised it.'

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 explicit guidance on when to use the tool ('Useful when the user has a technique in hand...') and names an alternative for deeper investigation ('Drill via atlas_case_study_lookup for the full procedure list'). This gives the agent clear decision criteria for choosing between these two siblings.

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