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 real context the annotations cannot: the confirm gate and preview fallback, the reassuring fact that existing content/formatting is preserved, and the OS-level permission caveat for Desktop/Documents/Downloads. It does not cover failure modes or error behavior, keeping it short of a 5.

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?

Four sentences, each earning its place: purpose, confirm behavior, permissions context, and sibling routing. The verb/resource and the safety-critical confirm rule are front-loaded, and there is 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 3-parameter mutation tool with an output schema present, the description covers what to call it for, how to safely trigger it, environment prerequisites, and where to go instead. Return shape is partly echoed but the output schema carries that burden, so nothing an agent needs 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 goes beyond the schema's terse "Must be true to modify" by explaining the actual consequence of omitting confirm — a preview is returned rather than a mutation. It adds no new syntax detail for `path` or `content`, so it is not a 5.

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 (append text to an existing .docx at `path`) plus the scoping constraint that existing content and formatting are preserved. It also explicitly distinguishes itself from the two nearest siblings, word_create and word_read, so an agent can route correctly without inspecting 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?

Gives explicit when-to-use routing ("To create a new document use word_create; to read one use word_read") and a concrete prerequisite/behavioral rule: confirm=true is required or the call returns a preview instead of modifying. Nothing about selection 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.