get_coverage

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

With no annotations, the description carries the full behavioral burden. It discloses a non-obvious behavior: an empty query result does not prove absence when unknown_coverage is true. This is a valuable caveat beyond the schema. It does not mention return format or side effects, but the core behavioral risk is addressed.

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 focused sentences: the first states what the tool does and its data source; the second adds a crucial edge-case warning. Every sentence earns its place, and the most important caveat is clearly highlighted.

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 is adequate for a one-parameter lookup, and the unknown_coverage caveat is valuable. However, there is no output schema, and the description does not explain the shape of the response, how unknown_coverage is represented in the result, or how this tool relates to the sibling query/list tools. This leaves some burden on the agent to infer behavior.

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 schema provides only a bare 'resource_type' string with no description. The tool description clarifies that the value refers to a resource type known to topology.yaml Icaria, which adds some context. However, it does not give allowed values, examples, or details on how the resource_type must be formatted, so compensation for the 0% schema coverage is only partial.

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 names a specific operation ('look up which observability surfaces cover') and a concrete data source ('from topology.yaml'). It also distinguishes itself from siblings like query_generic_source and list_generic_sources by focusing on coverage rather than generic querying or listing.

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 intended use is clear: call this tool when you need coverage information for a resource type. It even includes an important interpretive rule about empty results when unknown_coverage is true. It stops short of explicitly naming sibling alternatives or stating when not to use it, but the context is strong.

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