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

No annotations are supplied, so the description carries the full burden; it does help by labeling the operation 'Read' and naming the volatile fields it returns (live health, warning, callBlockers, lastRefused), which hints that values are computed at request time. It does not state authorization requirements, error behavior for unknown line IDs, or whether any side effect occurs on read.

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?

A single sentence with no filler, front-loaded with the verb and resource, followed by the return-value hints and the sibling pointer. Every clause earns its place.

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 two-parameter read tool with no output schema and no annotations, the description covers purpose, the payload fields returned, and the sibling alternative. The only meaningful gap is that neither required UUID parameter is explained beyond the phrase 'one phone line', which slightly limits confidence in calling it 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?

Schema description coverage is 0%, so the description must explain the two parameters and it does not: 'id' is only hinted at by 'one phone line', and 'workspaceId' (a required scoping parameter) is never mentioned. The agent must infer that id is the line UUID and that workspaceId scopes the lookup, which is not stated anywhere.

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 verb ('Read'), a specific resource ('one phone line'), and enumerates the distinguishing payload (live health, warning, callBlockers, lastRefused). The explicit pointer to lines.list separates it from the enumeration sibling, so an agent can choose between them without inspecting either schema.

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 '(see lines.list)' reference implicitly routes batch enumeration to the sibling and reserves this tool for single-record reads. It is clear usage context, but there is no explicit statement of when-not-to-use or of prerequisites such as needing the line to exist in the given workspace.

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