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

With no annotations, the description carries the burden of disclosing behavior. It explains the update/new-window semantics and the return value ('Returns the windowId for future updates'). However, it does not clarify whether multiple content types (html, mermaid, message, imageUrl) can be combined or if one takes precedence, leaving potential behavioral ambiguity.

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 three concise sentences, front-loaded with the core purpose. Every sentence adds valuable information: what it displays, how to update vs. open, and the return value. No unnecessary words or repetition.

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?

Despite no output schema and no annotations, the description covers the main operational aspects: display content, update vs. new window, and returns windowId. It does not explain the behavior when multiple content fields are provided simultaneously, which is a notable gap for a 6-parameter tool, but the description is otherwise sufficient for basic usage.

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?

The schema description coverage is 100%, so the baseline is 3. The description adds meaningful context for windowId by explaining its role in updating versus creating a window, which goes beyond the schema's simple description. It also groups content types, hinting at their usage, but does not detail interaction between parameters.

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 clearly states the tool's function: 'Display rich content (Markdown, HTML, Mermaid diagrams, images) in a window.' It uses a specific verb and resource, and further clarifies the update vs. new-window behavior based on the presence of windowId. This fully establishes the tool's purpose.

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?

The description gives concrete usage guidance: 'Pass windowId to update an existing window's content. Omit windowId to open a new window.' This tells the agent exactly how to choose between the two modes, though it does not mention alternatives or exclusions because there are no sibling tools.

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