Keel

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

With no annotations provided, the description carries full burden for behavioral disclosure. It mentions checking if a port is 'open' but doesn't explain what 'open' means (e.g., TCP handshake success), timeout behavior, error conditions, or what the output will contain. The default timeout parameter is documented in the schema but not explained in the description.

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, clear sentence with zero wasted words. It's front-loaded with the core purpose and appropriately sized for this simple tool.

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 network diagnostic tool with 3 parameters, 0% schema coverage, no annotations, and no output schema, the description is insufficient. It doesn't explain what constitutes an 'open' port, what the output format will be, error handling, or practical limitations. The context signals indicate significant gaps in documentation.

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%, so the description must compensate but adds no parameter information beyond what's obvious from names. It doesn't explain what 'host' accepts (hostname vs IP), valid port ranges, or timeout units (seconds). The baseline is 3 since schema coverage is low but description doesn't adequately compensate.

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 action ('check') and resource ('single TCP port on a host'), making the purpose immediately understandable. It distinguishes from siblings like 'port_scan' by specifying 'single' port, though it doesn't explicitly contrast with other network tools like 'ping' or 'http_check'.

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 no guidance on when to use this tool versus alternatives like 'port_scan' (for multiple ports), 'http_check' (for HTTP services), or 'ping' (for basic connectivity). It simply states what the tool does without contextual usage information.

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