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

Annotations already declare readOnlyHint=true and idempotentHint=true, reducing the burden. The description adds valuable behavioral nuance: 'Supports partial name matching — returns the best match if multiple facilities contain the query string.' This is beyond the annotations, though 'best match' is slightly vague about tie-breaking.

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 and deliverables, the second explains matching behavior, the third places it in the workflow. Information is front-loaded and each 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?

For a single-parameter, read-only, no-output-schema tool, the description covers the purpose, content, matching behavior, and usage context. With annotations handling safety and idempotency, nothing essential is missing for the agent to select and invoke it correctly.

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 coverage is 100%, so baseline is 3. The description enriches the 'name' parameter with matching semantics ('Supports partial name matching — returns the best match if multiple facilities contain the query string'), which is not fully expressed in the schema. It explains the behavior, not just the type/format, adding value over structured fields.

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 opens with a specific verb and resource: 'Get the full profile of one specific treatment facility' and enumerates exact contents (address, phone, programs, insurance, SAMHSA status, browse URL). It explicitly distinguishes itself from search_facilities by specifying drill-down intent, making it unmistakable among siblings.

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?

It gives explicit usage context: 'Use after search_facilities when the user wants to drill into a named facility.' This tells the agent exactly when to invoke it and implicitly when not to (i.e., not for searching or listing). It names the alternative tool, satisfying the top guideline bar.

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