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

Annotations already declare readOnlyHint, destructiveHint=false and openWorldHint, so safety is covered. The description adds real context beyond that: this returns only *incoming* calls and the exact field set, which matters because there is no output schema. It stops short of noting error behavior for a missing id.

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 short sentences, zero filler, and the identifying scope ('one incoming call by id') is front-loaded ahead of the field list and endpoint.

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 simple single-record GET with full schema coverage and annotations, the description is nearly sufficient, and enumerating return fields compensates for the absent output schema. Minor gap: no mention of what happens when the id doesn't resolve.

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?

With a single parameter at 100% schema coverage, the schema already documents call_id, its type, and its provenance. The description only repeats 'by id' and adds no format or constraint detail beyond the schema, so the baseline 3 applies.

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?

States a specific verb and resource ('One incoming call by id') and enumerates the fields returned (caller, called number, type, duration, contact, voicemail URL), plus the underlying REST path. An agent can distinguish it from placetel_list_calls without opening 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?

Usage is implied by 'by id', and the schema notes the id comes from placetel_list_calls, but the description itself names no alternative or exclusion. It never says what to do if the id is unknown or why to prefer this over list_calls.

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