create_tunnel

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

Annotations indicate write operation (readOnlyHint=false) and external effects (openWorldHint=true). Description crucially adds return value specification ('Returns the tunnel ID and public URL') which is essential given no output schema exists. Also adds validation constraints (1-63 chars) that affect behavior.

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 efficient sentences totaling ~20 words. First establishes action/resource, second covers validation and return value. Zero redundancy, perfectly front-loaded.

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 creation tool with external side effects (openWorldHint=true) and no output schema, the description adequately covers return values and input validation. Could briefly mention persistence or cleanup requirements (linking to 'delete_tunnel'), but covers core needs.

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?

Despite 100% schema coverage (baseline 3), description adds the length constraint '1-63 characters' which is absent from the schema's parameter description, providing necessary validation detail for the 'subdomain' parameter.

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?

Clear specific verb ('Register') plus resource ('tunnel subdomain'). Distinguishes from siblings like 'connect', 'list_tunnels', and 'delete_tunnel' by specifying this creates a new registration rather than managing existing connections or enumerating.

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?

Provides implied usage through the verb 'Register' (suggests initial creation vs connection), but lacks explicit when-to-use guidance or prerequisites (e.g., when to use this vs 'connect', or whether a tunnel must be created before connecting).

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