lookup_identity

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

Despite no annotations, the description fully discloses behavior: 'Read-only network call to AgentGraph API, no authentication required, no side effects. Typical response time under 500ms.' It also mentions edge cases ('Returns null fields if entity not found'). This satisfies the transparency requirement completely.

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 well-structured with separate sentences for purpose, return fields, behavior, usage, and edge cases. It is concise without unnecessary words, earning a score of 4 (a 5 would require even tighter phrasing, but this is already efficient).

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 single parameter and lack of output schema, the description is thorough: it covers the search query types, return fields, behavioral traits, network call details, typical response time, and null-handling behavior. Nothing essential is missing for the tool's complexity.

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 already describes the query parameter with 100% coverage. The description adds meaningful detail: 'DID lookup is exact match; name lookup uses case-insensitive prefix search.' This provides nuance beyond the schema, though the schema is already descriptive.

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: 'Look up an entity on AgentGraph by DID or display name.' It specifies the verb, resource, and input method, and distinguishes itself from siblings by indicating it is a prerequisite for tools like verify_trust and check_interaction_safety.

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: 'Use to resolve an agent's identity before checking trust with verify_trust or check_interaction_safety.' This tells when to use the tool, though it does not explicitly state when not to use it or list alternatives. However, given the sibling tool names, the context is clear.

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