Paid deterministic utilities and automation services for AI agents via MCP and x402.
Scored across 2 tools
The two tools have completely distinct purposes: one lists catalog items, the other checks service health. There is no overlap or ambiguity between them.
Both tools follow the same 'nexus_' prefix and verb_noun pattern (catalog, health). The naming is consistent and predictable.
With only 2 tools, the server feels thin for a utility toolkit. While the narrow scope might justify it, the count is borderline and likely insufficient for a comprehensive utility set.
The server only offers catalog listing and health check. For a utility server, one would expect additional operations such as retrieving details, managing resources, or performing actions. The surface is significantly incomplete for the implied domain.
List NEXUS x402 paid utilities
| Name | Required | Description | Default |
|---|---|---|---|
No parameters | |||
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries full responsibility for behavioral disclosure. The verb 'List' implies a read-only retrieval operation, but the description does not explicitly state safety, auth requirements, rate limits, output format, or any side effects. For a tool with zero annotation coverage, this is a significant gap.
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 5-word sentence that is front-loaded and free of fluff. It is appropriately concise but lacks any additional context that would normally be expected in a fuller description.
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?
Given no output schema and no annotations, the description is the only source for understanding return values and behavior. It does not mention what the list contains beyond 'paid utilities', nor any error conditions or data shape. For an agent to invoke this tool correctly, more context is needed.
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 input schema has zero parameters, so the baseline is 4. There is nothing to describe, and the description does not need to add parameter meaning. The empty schema already communicates that the tool takes no input.
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 specific verb and resource: 'List NEXUS x402 paid utilities'. It clearly indicates a listing operation on a defined resource. While it doesn't explicitly contrast with sibling nexus_health, the distinct resource name provides enough differentiation.
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 provides no guidance on when to use this tool versus alternatives like nexus_health. There is no mention of selection criteria, prerequisites, or scenarios where one should be chosen over the other. Given a sibling tool exists, this omission leaves the agent to infer the intended use.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Check NEXUS x402 service health
| Name | Required | Description | Default |
|---|---|---|---|
No parameters | |||
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, and the description only says 'check health' without disclosing details such as whether the operation is read-only, what it checks, expected response contents, or any potential side effects. The behavioral burden falls entirely on the description, and it is minimally met.
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, focused sentence with no filler. It conveys the essential purpose efficiently and is appropriately sized for a tool with no parameters.
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 parameterless health-check tool, the description is largely complete for invocation purposes. It could be improved by noting what a healthy versus unhealthy result looks like, but the absence of parameters and output schema makes this a minor gap.
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 and the schema coverage is 100%, so there is nothing for the description to add about parameter meaning. A baseline score of 4 is appropriate for a parameterless tool.
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 specific action ('check') and a clear resource ('NEXUS x402 service health'). This is distinct from the sibling tool nexus_catalog, so an agent can reliably select this tool for health-related queries.
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 implies the tool should be used when checking NEXUS x402 service health, which is a clear enough use case. However, it does not explicitly state when not to use it or mention alternative tools.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Recent tool additions, removals, and schema changes observed during successful MCP inspections.
nexus_catalognexus_health
Add one secure layer between your agents and this server.