tilwhen date engine

Subtract calendar days from a date

subtract_days

Read-onlyIdempotent

The date N whole calendar days before a date.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`tz`	No	IANA timezone that defines "today" (e.g. Africa/Kampala). Default UTC.	UTC
`date`	No	ISO date YYYY-MM-DD, or "today" (resolved in tz)	today
`days`	Yes

Output Schema

TableJSON Schema

Name	Required	Description	Default
`answer`	Yes	The calculated answer (kind-discriminated)
`receipt`	Yes	Auditable receipt: inputs, timezone, convention, workweek, holiday calendar, exclusions, versions, stable result ID

Schema Changelog

Changes observed during successful MCP inspections. Dates show when Glama detected each change.

First observedJul 26, 2026

TDQS

B3.4/5.0

Behavior3/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations indicate read-only, idempotent, non-destructive. Description adds that it uses calendar days and resolves 'today' in a timezone, but does not disclose that negative values effectively add days, which is a key behavioral nuance.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Single sentence that is front-loaded and contains zero unnecessary words. Highly concise.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a simple date manipulation tool with an output schema, the description provides core behavior. Missing mention of return format, but overall sufficient.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 67% (tz and date described, but days only has min/max). The description mentions 'N whole calendar days' but does not explain negative values or constraints beyond the schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description states the tool calculates a date N whole calendar days before a given date. It clearly distinguishes from siblings like add_days, but could be more explicit about subtraction.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines2/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

No guidance on when to use this tool versus alternatives like business_days or days_between. The description does not specify prerequisites or exclusions.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

All tilwhen date engine tools Inspect

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TDQS

A4.1/5.0

Disambiguation5/5

Each tool targets a distinct date operation: calendar addition/subtraction, business days, days between, holidays, invoice due, next occurrence, natural language parsing, and an explainer. No two tools overlap in purpose; descriptions clearly differentiate them.

Naming Consistency5/5

All tool names follow a consistent pattern: lowercase with underscores, predominantly verb_noun (add_days, parse_date_query) or noun_phrase (business_days, invoice_due). The naming is uniform and predictable.

Tool Count5/5

With 9 tools, the server is well-scoped. Each tool addresses a core date calculation need without redundancy or bloat. The count is appropriate for a focused date engine.

Completeness5/5

The tool surface covers all essential date operations: calendar arithmetic, business days, holidays, payment terms, next occurrences, and natural language queries. No obvious gaps remain for common date calculations.

Resources

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