Epa Emissions

Tri Trends

tri_trends

Read-onlyIdempotent

Analyze toxic release trends over time by state or chemical. Returns historical release data across years to identify patterns and changes.

Input Schema

TableJSON Schema

Name	Required	Description
`state`	No	Two-letter state abbreviation (e.g., "OH").
`chemical`	No	Chemical name (e.g., "LEAD").
`end_year`	No	End year for the trend range (default: most recent available).
`start_year`	No	Start year for the trend range (default: 5 years ago).

Output Schema

TableJSON Schema

Name	Required	Description
`state`	Yes	State abbreviation or null if not filtered
`trends`	Yes	Year-by-year release totals and facility counts
`chemical`	Yes	Chemical name (uppercase) or null if not filtered
`end_year`	Yes	Last year in the trend range
`start_year`	Yes	First year in the trend range

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedMay 8, 2026

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "properties": {
+    "chemical": {
+      "description": "Chemical name (uppercase) or null if not filtered",
+      "type": [
+        "string",
+        "null"
+      ]
+    },
+    "end_year": {
+      "description": "Last year in the trend range",
+      "type": "number"
+    },
+    "start_year": {
+      "description": "First year in the trend range",
+      "type": "number"
+    },
+    "state": {
+      "description": "State abbreviation or null if not filtered",
+      "type": [
+        "string",
+        "null"
+      ]
+    },
+    "trends": {
+      "description": "Year-by-year release totals and facility counts",
+      "items": {
+        "properties": {
+          "facility_count": {
+            "description": "Number of facilities with releases that year",
+            "type": "number"
+          },
+          "total_releases": {
+            "description": "Total quantity released that year",
+            "type": "number"
+          },
+          "year": {
+            "description": "Reporting year",
+            "type": "number"
+          }
+        },
+        "required": [
+          "year",
+          "total_releases",
+          "facility_count"
+        ],
+        "type": "object"
+      },
+      "type": "array"
+    }
+  },
+  "required": [
+    "state",
+    "chemical",
+    "start_year",
+    "end_year",
+    "trends"
+  ],
+  "type": "object"
+}

Changed1 schema field changedMay 6, 2026

addedInput schema / examples

Added value: +[
+  {
+    "end_year": 2023,
+    "start_year": 2018,
+    "state": "TX"
+  },
+  {
+    "chemical": "BENZENE",
+    "start_year": 2015
+  }
+]

First observedApr 22, 2026

TDQS

A3.8/5.0

Behavior3/5

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so the description's claim of returning historical data is consistent and adds moderate context. However, it does not elaborate on other behavioral traits such as pagination, data freshness, or the meaning of 'trends' beyond patterns, which would add value. No contradiction with annotations.

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?

The description is extremely concise at two sentences (16 words), front-loading the key action and scope. Every word contributes purpose, with no redundant or vague phrasing.

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?

Given the presence of an output schema and 100% parameter documentation, the description is mostly complete. It covers the core concept, but a slight gap remains: it does not clarify whether both state and chemical can be specified simultaneously or that at least one is needed (implied by examples but not stated). The date range defaults are handled in the schema, so overall it is adequate.

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 coverage is 100%, so baseline is 3. The description adds some contextual value by stating 'by state or chemical' and 'historical release data across years,' reinforcing that start_year and end_year define the range. However, it does not add new meaning beyond what the schema descriptions already provide for each parameter.

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?

The description clearly states the tool's purpose: 'Analyze toxic release trends over time by state or chemical.' It uses specific verbs ('analyze', 'returns') and resources ('trends', 'historical release data'), and the mention of 'by state or chemical' differentiates it from sibling tools like tri_chemical_releases and tri_facility_releases, which likely focus on individual releases rather than trends.

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

Usage Guidelines3/5

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

The description implies the tool is for trend analysis but does not explicitly state when to use it over siblings or when to avoid it. No guidance is provided on prerequisites, exclusions, or alternative tools, relying on the user to infer from the verb 'analyze trends' versus the siblings' likely focus on specific releases.

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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