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

Annotations already declare readOnlyHint=true and idempotentHint=true, covering the safety profile. The description adds valuable context about the curated directory size and specifies the exact return fields, which goes beyond the schema. It lacks details on pagination or error handling, but the annotations lower the bar, and the added context earns a 4.

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, each earns its place: the first defines the directory and filters, the second lists return fields, and the third gives usage flow with sibling tools. Highly concise and front-loaded.

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 the read-only/idempotent annotations and a fully descriptive schema, the description covers purpose, return fields, sibling tool flow, and prerequisite conditions. It provides enough context for an agent to select and invoke the tool correctly, even without an output schema.

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%, so all five parameters have detailed descriptions with types, defaults, and examples. The tool description recaps search dimensions but adds no new semantics beyond what the schema already provides. Baseline 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 a specific action ('Search') on a specific resource ('12,338 curated, SAMHSA-sourced US addiction treatment facility directory') with identifiable filters (state, city, treatment type, insurance). It also distinguishes itself from siblings by explicitly directing to get_facility_detail for full profiles and list_states for location coverage.

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?

Explicit guidance is provided: 'Use this to find candidates — then call get_facility_detail for one facility's full profile.' It also instructs when to call list_states first if location coverage is uncertain. This clearly states when to use the tool versus alternatives.

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