mpp_email_finderFind a person's email address given their name and company domain using MPP (Machine Payments Protocol). Pay-per-request, no API key required.
| Name | Required | Description | Default |
|---|---|---|---|
| domain | No | The domain of the company | |
| company | No | The company name | |
| full_name | No | The full name of the person | |
| last_name | No | The last name | |
| first_name | No | The first name |
| Name | Required | Description | Default |
|---|---|---|---|
| data | Yes |
Changes observed during successful MCP inspections.
Output schema / (root)Previous value: -nullNew value: +{
+ "$schema": "http://json-schema.org/draft-07/schema#",
+ "additionalProperties": false,
+ "properties": {
+ "data": {}
+ },
+ "required": [
+ "data"
+ ],
+ "type": "object"
+}Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover read-only and open-world intent, so the description only needs to add context; it adds a cost warning ('Pay-per-request') and an authentication fact ('no API key required'). Rate-limit and error details are absent, but the most important operational trait is disclosed.
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 deliver the core action, input pattern, protocol, cost model, and auth model without wasted words. The most decision-relevant information is front-loaded.
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 five parameters, none marked required, and an output schema present, the definition is mostly complete, but the missing required-input combination (e.g., which name field and whether domain, company, or both) is a real gap. An agent could under-specify the request or incur an unintended charge.
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 description coverage is 100%, so every parameter has an individual description and the baseline is 3. The description's 'name and company domain' phrase does not clarify whether full_name replaces or complements first_name/last_name, nor whether domain and company are both needed, though schema-level descriptions cover each field's basic meaning.
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 states a concrete action ('Find a person's email address'), the required input pattern ('name and company domain'), and the mechanism ('using MPP'). It also distinguishes itself from the non-MPP sibling 'email_finder' by noting 'Pay-per-request, no API key required.'
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?
It clearly signals when this variant is appropriate: pay-per-request and no API key needed. It does not explicitly name alternative tools or provide a 'when not to use' condition, so it stops short of a full routing guide.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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