faa-traffic-delays-mcp-server

List Active FAA Delay Events

faa_delays_list_active_events

Read-onlyIdempotent

List every active FAA traffic management event across the National Airspace System in one call: ground stops, Ground Delay Programs, Airspace Flow Programs, arrival and departure delays, airport closures, closure NOTAMs, and deicing. Rows are sorted by severity (closures, ground stops, then GDPs and then AFPs each by average delay, arrival/departure delays by band maximum, closure NOTAMs, deicing) and carry the reason, delay figures, times, and an advisory reference for faa_delays_get_advisory. Use faa_delays_get_airport_status for the full detail of one airport, including its GDP delay profile and runway configuration.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`event_types`	No	Only these event types: ground_stop, ground_delay_program, airspace_flow_program, arrival_delay, departure_delay, airport_closure, closure_notam, deicing. Also accepts gs, gdp, afp, spelled-out names such as "departure delay", and a comma-separated string; case-insensitive. Omit for every type. countsByType always covers the whole feed.

Output Schema

TableJSON Schema

Name	Required	Description
`error`	No	Present when the call failed. Absent on success.
`shown`	No	Events returned after the event_types filter.
`events`	No	Active events matching event_types, sorted by severity.
`notice`	No	Guidance on empty or partial results, stale delay entries, and how to get the missing data.
`fetchedAt`	No	When this server fetched the airport events from the FAA (UTC ISO); with the 60 s cache it can trail the call by up to a minute.
`enRouteFeed`	No	Whether Airspace Flow Programs were read: ok, unavailable (the en-route feed failed), or format_changed (it returned a format this server does not read).
`totalActive`	No	Every active event read, before the event_types filter; excludes AFPs when the en-route feed could not be read.
`countsByType`	No	Active events per type across the whole feed, counted before the event_types filter so types the filter excluded stay visible. airspace_flow_program is absent when the en-route feed could not be read.
`appliedEventTypes`	No	The event_types filter as the server normalized it, or every type when omitted.

Schema Changelog

Changes observed during successful MCP inspections.

First observedOct 2, 2026

TDQS

A4.4/5.0

Behavior4/5

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

Annotations already declare readOnlyHint, idempotentHint and openWorldHint, so the safety profile is covered. The description goes beyond that by disclosing the exact sort order (closures, ground stops, GDPs and AFPs by average delay, delays by band maximum, NOTAMs, deicing) and the payload each row carries (reason, delay figures, times, advisory reference), which materially shapes how an agent reads the result. It says nothing about rate limits or freshness/caching of the feed.

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

Conciseness4/5

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

Two sentences, with the scope-and-content statement front-loaded ahead of the sibling routing. The long parenthetical sort-order enumeration is dense but does real work for result interpretation; there is no filler.

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

Completeness5/5

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

With an output schema present, the description need not explain return values, and it still covers scope, ordering and onward navigation. Schema coverage, annotations and output schema together leave no gap an agent needs to call this correctly.

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 100% and the single optional event_types parameter is fully documented there, including aliases, comma-separated strings, case-insensitivity, and the note that countsByType always covers the whole feed. The prose adds no additional meaning about the filter, so the baseline 3 applies.

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

Purpose5/5

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

States a specific verb and resource with explicit scope ("every active FAA traffic management event across the National Airspace System") and enumerates the eight event classes it returns. It is unmistakably distinct from siblings that fetch a single airport, an advisory, or the operations plan.

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

Usage Guidelines5/5

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

Names the alternative for a concrete case: "Use faa_delays_get_airport_status for the full detail of one airport, including its GDP delay profile and runway configuration." It also routes the agent onward to faa_delays_get_advisory via the advisory reference carried in each row, so the when-to-use-this-vs-that decision is spelled out rather than inferred.

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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