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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered, and the description usefully clarifies that mutations come from the human in the UI ('change it by hand in 2D and 3D') plus that the view updates live. It omits key behavioral facts for a UI-opening tool: whether the call blocks or returns immediately, whether it requires an active user session, and what value comes back.

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?

Two sentences, no filler, and the primary action plus the interactive-editing behavior are front-loaded before the optional-parameter fallback. Every clause carries information the agent needs.

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 a single fully documented optional parameter, annotations covering the safety profile, and no output schema, the description covers what to pass and what happens when nothing is passed. The remaining gap is interaction lifecycle — whether opening the editor suspends the agent or returns a handle — which matters given this is a UI-invoking tool rather than a data read.

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 schema already explains where project_id comes from and that it must not be surfaced to the person, so the baseline is 3. The description earns above baseline by documenting the semantic effect of omitting project_id (a chooser of the person's plans), which is not expressed anywhere in the schema and is the only optional-parameter behavior an agent must reason about.

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 names a specific verb and resource ('Shows a plan in the Simple House Planner editor') and adds distinguishing detail that this is an interactive surface where the person edits in 2D/3D, which separates it from a plain read like describe_plan. It stops short of explicitly naming the sibling tools it differs from, so differentiation is implied rather than stated.

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?

One usage branch is given explicitly: 'Without a project ID it shows their plans to choose from,' which tells the agent the parameter is genuinely optional and what happens on omission. However, there is no guidance on when to prefer this over describe_plan, query_project, or list_projects, and no when-not conditions.

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