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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds genuine value by disclosing that results reflect live availability and that only active users are returned, though it says nothing about result volume, pagination, or ordering.

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 core purpose plus live-availability trait are front-loaded before the optional filter detail.

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 read-only list with one optional parameter and annotations covering safety, the description is nearly sufficient. The only gap is that, with no output schema, the shape of the returned user objects and the 'availability' field is never described.

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 100% and the single parameter is documented as 'Return only the user with this email address', so the failure mode the description must cover is small. The description's 'filter by email address' restates the schema rather than adding format or matching semantics (exact match vs 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?

States a specific verb and resource ('List active Spoke users') plus the distinguishing detail that results carry real-time availability. It does not explicitly contrast with siblings like spokephone_get_user or spokephone_list_location_users, so the boundary is inferred rather than stated.

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?

'List active Spoke users' implies inactive users are excluded, and 'Optionally filter by email address' hints at the narrowing path, but there is no explicit when-to-use guidance or routing to spokephone_get_user for single-lookup cases.

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