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

Annotations already flag destructiveHint=true and readOnlyHint=false, but the description adds context annotations cannot convey: that this writes to the customer's live TestRail, that confirmation is required first, and that labels behave as a replace rather than a merge with a recovery procedure. This is meaningful behavioral disclosure beyond the structured fields.

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?

Front-loaded with the core action, then ordered constraints (partial update, confirmation, label replace). Emphasis is used sparingly and each sentence carries an actionable rule; 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?

For a mutation tool with no output schema, the description covers the critical decision points: confirmation, partial-update semantics, and the label replace workflow. It stops short of describing the response or validation limits (e.g., title length, typeId/priorityId validity), though the schema already carries most field-level detail.

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; the description rises above it by explaining the omitted-field semantics (partial update) and the non-obvious REPLACE behavior of labels with the get-merge-call sequence, which materially changes how the agent should populate that array.

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 ("Update an existing TestRail test case") and clarifies the partial-update contract ("Any field omitted is left unchanged"), which cleanly distinguishes it from testrail_create_case and the read-only testrail_get_case siblings.

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?

Explicit when-to-use and a mandatory precondition ("ALWAYS confirm with the user via a chat bubble before calling"), plus an explicit alternative workflow that names the sibling testrail_get_case for the label-merge pattern. Nothing is left to inference.

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