draw

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

Annotations already declare it a safe read (readOnlyHint=true, openWorldHint=false), so the bar is lower. The description adds genuinely non-obvious behavior: the effect is client-dependent and is a silent no-op outside MCP Apps clients. It does not say what, if anything, is returned to the caller.

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 short sentences, purpose front-loaded, alternatives second. No wasted words, though the dense sibling shorthand ('report show', 'query look') trades clarity for brevity.

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?

Covers the essential decision points for a 4-optional-param, no-output-schema tool: when to use it, when not to, and what substitutes. It stops short of explaining what a 'view' or 'the map'/'type lens' entity is, leaving some conceptual gaps for the agent.

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 each parameter is described in the schema, including the nested style shape { layout, lit, id }, so the baseline is 3. The description adds no parameter guidance of its own and only cross-references sibling tools ('as query flat takes it').

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 ('Draw a view in this chat') plus the audience ('for the person reading it') and the platform precondition (an MCP Apps client such as Claude chat). The term 'view' is undefined jargon, but the platform constraint and the contrast with siblings make the intent legible.

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?

Explicitly covers the when-not case ('Elsewhere nothing is drawn') and names the concrete alternatives with their differing behavior: 'report show opens it on their canvas, query look gives you the picture.' An agent can pick the right tool without opening any schema.

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