search_available_numbers

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

No annotations are provided, so the description must carry the full burden of behavioral disclosure. It does a good job: it explains search behavior (inference of searchby modes), the return format (compact rows with specific fields), and instructs the agent to show results to the user before buying, which is a behavioral expectation. However, it doesn't disclose potential side effects (e.g., whether this is a read-only operation) or rate limits, but the description is still informative.

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 bullet points for different modes, making it easy to scan. It fronts the purpose and then provides essential details without redundancy. Every sentence adds value: it explains modes, international usage, return fields, and next steps. It's concise yet comprehensive for a tool with many parameters.

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 tool's complexity (9 optional parameters, no output schema), the description is quite complete: it covers the main search modes, international options, return fields, and the expected workflow (show results to user). However, it doesn't explain the meaning of all return fields (e.g., lata, hipaa_friendly) or account_id/token_name usage, which could be critical for correct invocation in some scenarios. Minor gaps remain.

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 0%, meaning the schema provides no descriptions for parameters. The description explains the semantics of area_code, address, number_prefix, searchby, and country/operator/pattern, which are the main parameters. However, it does not explain account_id or token_name, which are likely identifiers for multi-tenant use. Given the low coverage, the description compensates partially but misses some parameters, warranting a 3.

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 a specific verb ('Search') and resource ('available CTM tracking numbers') and distinguishes the tool's purpose from buying them, explicitly saying 'before buying them' and later 'let them pick before calling buy_numbers'. This differentiates it from sibling tools like buy_numbers. The scope (US/CA and International modes) is clearly outlined, making the purpose unambiguous.

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 on when to use the tool: it is for searching before buying, and it explains how searchby modes are inferred when omitted. It also mentions the alternative (buy_numbers) implicitly, but doesn't explicitly state when NOT to use it or name alternatives beyond 'buy_numbers' in the last line. Sibling tools like configure_numbers and release_numbers are not mentioned as alternatives, but the description's context is sufficient for most agents.

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