Creates a histogram by counting the frequency of data points falling into specified bins or ranges. Returns the frequency count for each bin. (cost: 1 credit)
| Name | Required | Description | Default |
|---|---|---|---|
| bins | No | integer or array, required, number of bins or array of bin edges | |
| data | No | array of numbers, required, data points to create histogram from |
Changes observed during successful MCP inspections.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnly/idempotent/non-destructive, and the description stays consistent while adding two pieces of information the annotations do not carry: the cost ('1 credit') and the shape of the result ('frequency count for each bin'). It does not discuss error handling for non-numeric or out-of-range data, but for a read-only computation that is a minor 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?
Two tight sentences that front-load the operation and then the return value, with the cost note appended in parentheses. Nothing is wasted, though the second sentence slightly repeats the counting idea from the first.
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 no output schema, the description usefully states what is returned, and the schema fully covers the two inputs; cost is also disclosed. Missing only edge-case behavior (empty data, non-numeric input, how bin count vs. bin edges interact), which keeps it from a 5.
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%, so both parameters (bins, data) are already documented, including the integer-or-edge-array duality for bins. The description only restates 'specified bins or ranges' without adding syntax, defaults, or ordering rules, so the baseline 3 applies.
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 uses a specific verb+resource pair ('Creates a histogram') and elaborates the mechanism ('counting the frequency of data points falling into specified bins or ranges'), which is enough for an agent to distinguish it from generic calculators like average or calculate_median. It stops short of explicitly naming any sibling tool, but no sibling competes for the same operation.
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?
Usage is implied by the description itself: use it when you need frequency counts per bin rather than summary statistics. There is no explicit when-to-use/when-not-to-use guidance or pointer to an alternative for agents deciding between this and the summary-statistics tools.
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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