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

Annotations already declare read-only, idempotent, non-destructive, and closed-world behavior. The description adds meaningful operational details beyond those annotations: enumeration is bounded to five pages, ambiguity or incomplete enumeration returns candidates, and no message or friend request is sent.

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 written sentences, front-loaded with the action and scope. Every clause carries useful behavioral or safety information.

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 simple two-parameter resolver with rich read-only annotations and no output schema, the description explains the key return contract: candidates rather than a selection, plus the five-page bound. It stops short of describing candidate fields or exact output shape, but the core decision information is present.

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 50% schema coverage, the required 'name' parameter is only documented as a minLength string in the schema; the description clarifies it means a name inside the owner's friends. The optional account_id is fully described in the schema, so the description need not repeat it, but it adds no further parameter guidance.

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?

States a specific verb ('Resolve') and resource ('a name in the account owner's friends'), plus the five-page scope. This differentiates it from profile lookup and list-friends siblings by confining resolution to the owner's friend graph and clarifying that it only returns candidates.

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 implies the use case of resolving a friend's name when multiple candidates may exist, and notes that it will not select anyone or send messages. However, it does not explicitly name alternatives such as facebook_get_profile or facebook_list_friends, nor state when not to use it.

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