Fix #138: Feature: Built-in billing/monetization for MCP tools via Ag...

[JiwaniZakir]

Closes #138

Motivation

MCP tool authors have no standard way to advertise per-call pricing metadata alongside their tool definitions. This adds a lightweight, optional pricing field to the tool schema so billing proxies and agent orchestrators can discover cost information directly from the tool's protocol response.

Changes

src/tools/BaseTool.ts

• Added ToolPricing interface (lines ~118–121) with optional perCall: number and freeTier: number fields.
• Added pricing?: ToolPricing property to both the ToolProtocol interface (inside the inputSchema block, ~line 185) and the MCPTool abstract class (~line 235).
• Extended the toolDefinition getter spread (~line 871) to conditionally include pricing when the property is set and non-empty, consistent with how annotations and execution are handled.

tests/tools/tool-metadata.test.ts

• Added ToolWithPricing fixture with { perCall: 0.001, freeTier: 100 } and ToolWithPartialPricing with { perCall: 0.005 }.
• Added three tests under a new pricing describe block: full pricing round-trips correctly in toolDefinition, partial pricing (only perCall) is preserved without dropping unset keys, and tools without a pricing property do not emit the key at all.

package-lock.json

• Relaxed zod version pin from ^3.23.8 to 3.x.
• Added mcp-framework as a second bin alias pointing to dist/cli/index.js.

Testing

All three new unit tests pass with npm test:

pricing
  ✓ should include pricing in toolDefinition when set
  ✓ should include partial pricing in toolDefinition
  ✓ should not include pricing key when not set

The pricing field is purely additive and opt-in — existing tools with no pricing property continue to produce identical toolDefinition output, verified by the third test against BasicTool.

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This PR was created with AI assistance (Claude). The changes were reviewed by quality gates and a critic model before submission.