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

readOnlyHint=true already tells the agent this is a safe read, so the bar is lower. The description adds the underlying REST endpoint (GET /{account}/group_filters/{filter}/groups), which reveals the resource hierarchy that `group_filter` maps to, but says nothing about pagination behavior or result size limits even though a `cursor` param exists.

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 plus an endpoint reference, with the core purpose front-loaded. The API route is arguably redundant with the naming of the resource, but it is brief and does add traceability.

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 tool with one required parameter, full schema coverage, and no output schema, the description covers resource, scope, and search. The only real gap is how to interpret/iterate results, which the cursor param partly implies.

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%, so all four parameters are already documented in the schema, including the `mine` default and the cursor's provenance. The description adds only marginal framing ('search group names', 'group folder') and does not explain the `q` 'phone digits' matching or the relationship between group_filter and filter slugs beyond schema text.

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 contact groups in a group folder') and clarifies the two folder scopes ('mine' or account groups), which separates it from the similarly named sibling textus_list_group_contacts. It never explicitly names that sibling, so differentiation is inferable 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?

The only usage-like sentence ('Use `q` to search group names') is parameter guidance, not situational guidance. There is no statement of when to call this versus textus_list_group_contacts or textus_list_contact_filters, and no prerequisites or exclusions.

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