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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, covering the safety profile. The description adds valuable context about the exact content returned (base URLs, attribution headers, non-proxied shapes), going beyond what annotations imply. It does not contradict 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 a single, information-dense sentence that front-loads the core purpose ('Return every provider...') and then lists specific details. Every clause adds value, though it is slightly longer than the minimal necessary, so it earns a 4 rather than a 5.

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 read-only list tool with no parameters and no output schema, the description is fully sufficient. It enumerates all return categories and the routing directive, leaving no gaps an agent would need to fill.

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 tool has zero parameters, so the schema is trivially fully covered. The description adds no parameter details because none exist; the baseline of 4 for a zero-parameter tool 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 explicitly states the tool returns every provider Spendline can proxy, the three request shapes, base URLs, attribution headers, and non-proxied shapes. It uses a specific verb 'Return' and names the resource, clearly distinguishing it from sibling tools that check status or create budgets.

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 directive 'Resolve routing from here instead of hardcoding it' explicitly tells agents when to use this tool as the authoritative source for provider and routing details. It leaves no ambiguity about when to invoke it, even without naming alternatives.

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