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, and the description adds genuinely non-obvious context: the records contain personal data and callers should minimize the fields/filters requested. It also discloses the backing endpoint (GET /users). It stops short of describing pagination behaviour or defaults, which the schema partially covers.

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 compact sentences, front-loaded with the resource and its filters, followed by the single most important caveat (personal data). No filler, no restatement of the title.

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?

With 13 parameters, no output schema and only readOnlyHint for annotations, the description covers purpose and privacy adequately but never says what a returned user record looks like or how results are ordered/paged beyond the schema's since_id hint. Adequate to call correctly, but not complete for a wide, PII-bearing list endpoint.

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 13 parameters are already documented with examples and enum values in the schema, which sets the baseline at 3. The description only re-summarizes three filter families (status, name, email) and omits the date, paging, and 'show_inactive' semantics, adding little beyond the structured fields.

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 states a specific verb and resource ('List site users (volunteers)') plus the filterable dimensions (status, name, email), which is a real improvement over the bare title 'List users'. It does not explicitly differentiate from near-neighbours such as galaxydigital_get_user or galaxydigital_list_user_agencies, so an agent must infer the boundary from the list/get naming convention.

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?

There is no statement of when to use this tool versus alternatives like galaxydigital_get_user (single lookup) or galaxydigital_list_user_agencies, and no prerequisites or paging guidance. 'Ask for only what the task needs' is a data-minimization instruction about how to call it, not when to choose it, so it does not satisfy the usage-guideline burden.

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