Resolve User Keys

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

Annotations already declare readOnly, openWorld, and idempotent behavior. The description adds a small amount of context about canonicalization and use with write tools, but does not disclose edge-case behavior such as what happens when identifiers cannot be resolved or whether partial results are returned. With the safety profile covered by annotations, a 3 is appropriate.

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 a single, information-dense sentence. It immediately states the core action and purpose, with zero wasted words or redundancy with the schema.

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 resolution tool with rich annotations and a fully described schema, the description covers the essential purpose and usage context. However, with no output schema, the description does not explicitly state the return format or behavior for unresolved identifiers, which is a minor gap in completeness.

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% parameter coverage with clear descriptions for all three parameters. The tool description itself adds no additional parameter semantics beyond what the schema already provides, so the baseline of 3 applies.

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 uses a specific verb 'resolve' against a clear resource (names/emails/aliases into canonical user_key values). It immediately distinguishes itself from sibling tools like user_search by focusing on canonical key resolution for write tools, not general user search.

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 phrase 'so write tools can safely fill user fields and role assignments' clearly implies when to use this tool: before write operations needing user keys. It provides useful context without explicitly naming alternatives, but the purpose inherently points to the right usage scenario.

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