Keel

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

With no annotations provided, the description carries full burden and does well by disclosing key behavioral traits: it describes the test methodology (downloads 10 MB payload from Cloudflare, uses TCP connect pings), what gets measured (download speed in Mbps, latency stats in milliseconds), and the operation's read-only nature. However, it doesn't mention potential rate limits, timeout behavior, or error conditions.

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 perfectly concise with four sentences that each earn their place: first states the overall purpose, second explains the download test methodology, third explains the latency methodology, fourth specifies the return format. No wasted words, well-structured, and front-loaded with the core purpose.

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 moderate complexity (network testing with specific methodology), no annotations, and no output schema, the description does quite well by explaining what gets tested, how it's tested, and what values are returned. However, it doesn't describe the exact structure of the latency stats or potential error scenarios, leaving some gaps for a tool with no structured output 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?

The tool has zero parameters with 100% schema description coverage, so the baseline would be 4. The description appropriately doesn't discuss parameters since none exist, and instead focuses on the tool's behavior and output.

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 purpose with specific verbs ('measure network download speed and latency') and resources ('downloads a 10 MB test payload from Cloudflare'). It distinguishes itself from sibling tools like 'ping' (which might measure latency only) or 'http_check' (which checks HTTP status) by focusing specifically on comprehensive network performance testing.

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 implies usage context (network performance testing) but doesn't explicitly state when to use this tool versus alternatives like 'ping' for latency-only checks or 'http_check' for HTTP-specific diagnostics. It clearly indicates what the tool does, but lacks explicit guidance on tool selection among network-related siblings.

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