reachability

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

With no annotations, the description carries the full burden. It discloses that the tool reads raw events, warns about cost, and defines the outage-window threshold as >=5% of peers routeless. It also explains that multi-prefix events resolve in one call. This is meaningful behavioral context beyond the schema.

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?

Four short sentences, front-loaded with the core answer and return shape. Each sentence adds a distinct fact: what is counted, what is returned, multi-prefix behavior, and a cost warning. No filler or redundancy.

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?

The description explains the output type and threshold, which is useful given no output schema. However, it leaves important invocation details underspecified, especially start/end format and defaults, and does not describe the structure of the event-driven series well enough for an agent to interpret the result confidently.

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. It explains that prefixes are multiple and implies start/end define a time window via 'keep the window tight,' but it does not explain their optionality, value format, defaults, or how they interact with the returned series. Parameter semantics remain under-specified.

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 computes how many observing peers had no route and when, and that it returns an event-driven series plus server-computed outage windows. It also highlights multi-prefix support, which distinguishes it from sibling tools focused on paths, visibility, or timeline analysis.

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 gives explicit practical guidance: use multiple prefixes in a single call for multi-prefix events, and keep the time window tight because the tool reads raw events. It does not name alternatives or explicitly say when not to use it, so it misses the top tier, but the context is clear.

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