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

readOnlyHint=true already establishes this is a safe read. The description only adds the REST endpoint (GET /groups/{group}/contacts), which is mildly useful context but says nothing about pagination behavior or return shape beyond what the cursor parameter already implies.

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, front-loaded with the action and resource. The endpoint sentence is low-value but costs almost nothing in length.

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?

A simple two-parameter read tool with full schema coverage and readOnly annotations; the description is adequate for calling it correctly. A brief note that results are paginated via cursor would round it out.

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%, with both group and cursor fully documented in-schema. The description adds no parameter detail beyond restating the path template, 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 ('List the contacts that belong to a group') and scopes it to group membership, which implicitly separates it from textus_list_contacts. It does not name that sibling explicitly, so the differentiation is left to inference.

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 group-scoped framing implies when to use it (you have a group id and want its members), but there is no explicit when/when-not guidance and no mention of textus_list_contacts as the alternative for all contacts.

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