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

Annotations already convey read-only and non-destructive behavior, but the description adds substantial context beyond them: client-side filtering, no server-side cap on the upstream endpoint, automatic passthrough of new columns, and no row reshaping. It even warns against fetching unbounded history, which is actionable behavioral guidance.

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 dense but well organized: purpose, row shape, usage context, filter semantics, permission, and example. Every sentence provides operational value, and the core answer to 'what does this do' comes first.

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?

With no output schema, the description compensates by describing the row shape, typical fields, ordering, dynamic column behavior, and the fact that rows are passed through unmodified. It also covers permission and gives a concrete invocation example, so an agent has enough context to call the tool correctly.

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 input schema already documents ranges and defaults for both parameters, so the baseline is 3. The description adds meaningful extra context by noting the filters are client-side, explaining that the upstream returns the full history with no cap, and recommending narrowing with hours to avoid unbounded fetches. This goes beyond the schema's static definitions.

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 returns recent WAN speedtest results ordered by timestamp, answers a specific user question about internet health, and maps to a concrete endpoint. It also distinguishes itself from ping/traceroute/netflow by naming the exact scenario (WAN throughput trends) where it applies.

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?

Explicitly states when to use it versus alternatives: it is lower priority than ping/traceroute/netflow for general 'internet slow' investigations, but the right tool when the user asks about WAN throughput trends or recent speedtest runs. This gives the agent a clear selection rule.

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