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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds genuinely new context: this opens a live connection, is app-only, and is hidden from the model by supporting clients. It does not disclose connection lifetime or what the returned ticket is for, which is the remaining gap.

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?

One sentence, front-loaded with the usage restriction and immediately followed by the reason the model won't see it. 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 one-parameter, annotation-covered, app-internal tool this covers what an agent needs: what it does and who calls it. The only omission is what the tool returns (a connection ticket) and its lifetime, though the name plus 'live connection' imply it.

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% and the single diagramId parameter is documented in-schema with its source (list_diagrams or create_diagram). The description adds no further meaning, which is the expected baseline when the schema does the work.

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 ('open a live connection') and scopes it to the in-chat viewer (MCP App), so an agent can tell this is an app-internal connection tool rather than a diagram-content tool. It does not explicitly contrast with the closely related sibling viewer_poll, which is the only nearby ambiguity.

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 a clear when/when-not: 'Used only by the in-chat viewer' plus the note that app-only-capable clients hide it from the model, which effectively tells the model not to call it. It stops short of naming what the model should use instead (e.g., viewer_poll or show_diagram).

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