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

Annotations already cover safety (readOnlyHint=true, destructiveHint=false). The description adds valuable behavioral context: the tool accesses only 'Public registration sections' and explains the optional SAM.gov API key behavior (spending your own quota and skipping the shared budget). This goes beyond the annotations by disclosing scope and rate-limit considerations, though it doesn't cover all potential response details or error handling.

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 concise and well-structured: a single opening sentence states the core function and returns, followed by concrete use cases, and a final scope limitation. Every sentence adds value with no fluff or repetition, front-loading the most critical 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?

The tool has no required parameters and no output schema, so the description must convey what the tool returns and its limitations. It lists the returned data fields and notes the public-only scope, which is sufficient for a simple read-only lookup. It also addresses the API key option, which is relevant for usage context. It might have been improved by explicitly mentioning the response format, but given the low complexity, it is nearly complete.

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 the schema already documents all three parameters (UEI, name, sam_api_key) with their descriptions. The tool description adds minimal parameter-specific info beyond restating that lookup can be by UEI or name. It doesn't clarify behavior when both are provided or any precedence, so it stays at the baseline for high schema coverage.

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 a federal contractor registration in SAM.gov by Unique Entity ID (UEI) or legal business name' with a specific verb ('look up') and resource ('federal contractor registration'). It also lists the returned fields (registration status, CAGE code, address, business types, NAICS codes), distinguishing it from sibling tools like find_agency or get_award.

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 usage scenarios: 'Call this to vet a teaming partner, check a competitor, or confirm an entity is award-eligible.' It also notes a limitation: 'Public registration sections only.' However, it does not explicitly state when not to use it or name alternative tools, missing the full 'when/when-not/alternatives' criterion for a 5.

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