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

Annotations cover the safety profile (readOnly/idempotent/non-destructive), and the description layers on the behaviors that matter: server-side pagination so the caller never handles offsets, a default compact output mode with a stated reason (full form overruns the output limit), a hard cap of 20 pages/5000 cases, and a capReached signal to check. This is substantive context beyond the annotations.

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?

Three sentences, front-loaded with the core action and scope, then the output/pagination caveat, then the alternative-tool pointer. Every clause carries decision-relevant information with no filler.

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, the description still characterizes the return shape (compact id+title rows by default), the cap, and the capReached indicator, so an agent knows what to expect and how to detect truncation. Nothing needed to invoke it correctly is missing.

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 coverage is 100%, so the baseline is 3, but the description adds real meaning: it explains WHY compact defaults to true (output-limit overrun) and constrains compact:false to a narrow sectionId. The scoping params (projectId/suiteId/sectionId) are only echoed from the schema.

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 EVERY case in a TestRail project/suite/section') and immediately distinguishes itself from the paginated sibling by noting it walks all pages server-side. An agent can tell it apart from testrail_list_cases and testrail_find_cases without opening any schema.

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?

Explicitly routes to alternatives: use testrail_find_cases for an existence check because it is 'far cheaper', and use compact:false 'only for a narrow sectionId'. Both when-to-use and when-not conditions are stated.

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