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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false. The description adds useful context by confirming it 'does not draw or mutate a canvas' and enumerating the validation domains (nodes, edges, owners, viewport policy, accessibility, source references, receipt-binding). No contradiction with annotations.

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 two sentences with no fluff. The first sentence states the core purpose, and the second efficiently lists the key validation areas and the critical non-mutation boundary. Every clause adds value.

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?

The tool is a validation-only operation with a rich output schema, so the description does not need to explain return values. It gives the validation scope and explicitly notes non-mutation. Minor gaps exist (e.g., doesn't mention optional schema fields like groups, labels, render_policy), but overall it is sufficient for an agent to select and invoke correctly.

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?

There is only one parameter ('contract') and the schema description covers 100% of it, including nested fields. The tool description mentions some validated fields (nodes, edges, owners, etc.) but does not add meaningful parameter semantics beyond what the schema already provides, so the baseline of 3 is appropriate.

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 uses a specific verb ('Validate') plus a clear resource ('canonical StrategiX visual-spec contract') and states the exact timing ('before rendering'). It also distinguishes from sibling tools by explicitly noting it 'does not draw or mutate a canvas', which separates it from strategix_diagram_render.

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 clearly indicates when to use the tool ('before rendering') and gives a boundary ('does not draw or mutate a canvas'). However, it does not explicitly name alternative tools or state when not to use it, so it falls short of a 5.

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