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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered structurally. The description adds nothing beyond the endpoint path except the pointer to describe_operation; it says nothing about return shape, 404 behavior for missing unit/site, or pagination.

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?

The description is two nearly identical sentences — the endpoint path is repeated verbatim, which is pure waste. It is short but redundant and back-loads the only additional information (the operation ID and describe_operation pointer) into a trailing clause.

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 no output schema and 0% parameter description coverage, this tool depends on the description to say what is returned and what the path parameters mean. Instead it repeats the URI and defers all real detail to describe_operation, leaving an agent unable to predict the response shape or error conditions.

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 0% and the description never explains siteId, unitId, or the free-form query object. The path template at least maps :siteId and :unitId to the two required params, which is marginal value, but constraints like minLength/maxLength and the semantics of the 'query' bag are left entirely undocumented.

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 REST path 'GET /api/sites/:siteId/units/:unitId' does convey a specific verb and resource (fetch one unit scoped to a site), which is more informative than the tool name alone. However, the description offers no explanation of what a 'unit' is, and it does not differentiate itself from the closely related sibling get_sites_by_siteId_units (which lists units) — an agent must infer the singular-vs-collection distinction from the path shape.

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 get_sites_by_siteId_units, get_sites_by_id, or the generic execute_read. The only guidance-like content is a pointer to describe_operation for native request schemas, which is a schema-lookup hint rather than usage guidance.

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