ArcFlow exposes the Destiny Matrix numerology calculator as MCP tools. Given a date of birth it returns a structured reading (core numbers 1–22 for personality, talents, money, relationships, life purpose and karmic patterns, each with a short interpretation) plus a rendered octagram image. A second tool computes compatibility between two birth dates. Deterministic, read-only, no auth.
Scored across 2 tools
The two tools have clearly distinct purposes: one calculates a single person's matrix, the other calculates compatibility between two people. There is no overlap or ambiguity.
Both tools follow the same `calculate_` verb-noun pattern, making the naming perfectly consistent and predictable.
With only 2 tools, the set is minimal but not inappropriately so, given the narrow domain of Destiny Matrix numerology. Both essential operations are covered.
The core functionality of the domain is covered: individual matrix calculation and compatibility assessment. No obvious missing features for a basic numerology server, though additional tools like number interpretation or detailed breakdowns could be added.
Calculate relationship compatibility between two people from their dates of birth, using the Destiny Matrix numerology method. Returns a structured reading of the couple: shared core numbers plus text interpretations for relationship dynamics, finances, conflict points, children, and growth areas. Use this when a user asks how compatible two people are, or wants a numerology compatibility reading based on two birth dates.
| Name | Required | Description | Default |
|---|---|---|---|
| locale | No | Language for the text interpretations: "en" (default), "ru", or "es". | |
| birthdate_a | Yes | First person's date of birth in DD-MM-YYYY format, e.g. "15-05-1990". | |
| birthdate_b | Yes | Second person's date of birth in DD-MM-YYYY format, e.g. "20-08-1995". |
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true, and the description adds useful behavioral detail about the return structure (couple's shared core numbers plus text interpretations for relationship dynamics, finances, conflict points, children, growth areas). It doesn't contradict annotations and goes beyond them by describing output composition.
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?
Three sentences, each earning its place: a clear action sentence, a return-value sentence, and an explicit usage sentence. No filler, no repetition, and the most important 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?
Despite lacking an output schema, the description adequately explains what the tool returns (structured reading with specific areas). Combined with comprehensive parameter descriptions in the schema and read-only annotations, the description is complete for an agent to select and invoke the tool 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?
Schema coverage is 100%, with each parameter already described (birth dates in DD-MM-YYYY format, locale enum). The description doesn't add extra parameter semantics beyond mentioning 'two birth dates', so it aligns with the baseline where the schema does the heavy lifting.
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 clearly states the tool calculates relationship compatibility from two birth dates using the Destiny Matrix method. It specifies the output (shared core numbers plus text interpretations for dynamics, finances, conflict points, children, growth areas) and distinguishes from a generic matrix calculation.
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 explicitly says 'Use this when a user asks how compatible two people are' and mentions a numerology compatibility reading, providing clear context. It doesn't name the sibling tool as an alternative or state exclusions, so it lacks a direct when-not-to-use, but the usage direction is strong.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Calculate a Destiny Matrix (also known as "Matrix of Destiny" or numerology matrix) from a single date of birth. Returns a structured numerology reading: core numbers (1–22) for personality, talents, money, relationships, life purpose, and inherited/karmic patterns, each with a short text interpretation. Use this when a user asks to compute, build, or interpret a destiny matrix, or wants a numerology personality reading based on a birth date.
| Name | Required | Description | Default |
|---|---|---|---|
| locale | No | Language for the text interpretations: "en" (default), "ru", or "es". | |
| birthdate | Yes | Date of birth in DD-MM-YYYY format (day-month-year), e.g. "15-05-1990". |
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true, so the description doesn't need to cover safety. It adds value by describing the output structure (core numbers 1–22, text interpretations) and the scope (personality, talents, money, relationships, etc.), which goes beyond the basic read-only nature.
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 well-structured sentences that front-load the main purpose, then detail the output, and finish with a usage guideline. No wasted words, and the key information is presented efficiently.
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?
There is no output schema, so the description takes on the burden of describing return values. It does so thoroughly (core numbers, interpretation categories). However, it doesn't mention edge cases like invalid date formats or whether the locale parameter affects the output format, leaving minor gaps.
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 the schema already documents both parameters (birthdate and locale). The description mentions 'single date of birth' but adds no additional parameter semantics beyond the schema, earning the baseline score of 3.
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 clearly states the tool calculates a Destiny Matrix from a date of birth and returns a structured numerology reading with specific components (core numbers, personality, talents, etc.). It also explicitly distinguishes its use case from the sibling tool by mentioning 'numerology personality reading based on a birth date.'
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 an explicit 'Use this when...' clause listing the relevant user requests. However, it does not directly mention when not to use it or name the sibling tool (calculate_compatibility) as an alternative, leaving some ambiguity.
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.
calculate_compatibilitycalculate_matrix
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