diff --git a/autogpt_platform/backend/backend/api/features/chat/tools/agent_search.py b/autogpt_platform/backend/backend/api/features/chat/tools/agent_search.py
index 5fa74ba04e..86bab267c1 100644
--- a/autogpt_platform/backend/backend/api/features/chat/tools/agent_search.py
+++ b/autogpt_platform/backend/backend/api/features/chat/tools/agent_search.py
@@ -1,10 +1,11 @@
 """Shared agent search functionality for find_agent and find_library_agent tools."""
 
 import logging
-from typing import Literal
+from typing import Any, Literal
 
 from backend.api.features.library import db as library_db
 from backend.api.features.store import db as store_db
+from backend.data import graph as graph_db
 from backend.util.exceptions import DatabaseError, NotFoundError
 
 from .models import (
@@ -20,6 +21,44 @@ logger = logging.getLogger(__name__)
 SearchSource = Literal["marketplace", "library"]
 
 
+async def _fetch_input_schema_for_store_agent(
+    creator: str, slug: str
+) -> dict[str, Any] | None:
+    """Fetch input schema for a marketplace agent."""
+    try:
+        store_agent = await store_db.get_store_agent_details(creator, slug)
+        graph_meta = await store_db.get_available_graph(
+            store_agent.store_listing_version_id
+        )
+        graph = await graph_db.get_graph(
+            graph_id=graph_meta.id,
+            version=graph_meta.version,
+            user_id=None,
+            include_subgraphs=False,
+        )
+        return graph.input_schema if graph else None
+    except Exception as e:
+        logger.warning(f"Failed to fetch input schema for {creator}/{slug}: {e}")
+        return None
+
+
+async def _fetch_input_schema_for_library_agent(
+    graph_id: str, user_id: str
+) -> dict[str, Any] | None:
+    """Fetch input schema for a library agent."""
+    try:
+        graph = await graph_db.get_graph(
+            graph_id=graph_id,
+            version=None,  # Get latest version
+            user_id=user_id,
+            include_subgraphs=False,
+        )
+        return graph.input_schema if graph else None
+    except Exception as e:
+        logger.warning(f"Failed to fetch input schema for graph {graph_id}: {e}")
+        return None
+
+
 async def search_agents(
     query: str,
     source: SearchSource,
@@ -55,6 +94,10 @@ async def search_agents(
             logger.info(f"Searching marketplace for: {query}")
             results = await store_db.get_store_agents(search_query=query, page_size=5)
             for agent in results.agents:
+                # Fetch input schema for the agent
+                input_schema = await _fetch_input_schema_for_store_agent(
+                    agent.creator, agent.slug
+                )
                 agents.append(
                     AgentInfo(
                         id=f"{agent.creator}/{agent.slug}",
@@ -67,6 +110,7 @@ async def search_agents(
                         rating=agent.rating,
                         runs=agent.runs,
                         is_featured=False,
+                        inputs=input_schema,
                     )
                 )
         else:  # library
@@ -77,6 +121,10 @@ async def search_agents(
                 page_size=10,
             )
             for agent in results.agents:
+                # Fetch input schema for the agent
+                input_schema = await _fetch_input_schema_for_library_agent(
+                    agent.graph_id, user_id  # type: ignore[arg-type]
+                )
                 agents.append(
                     AgentInfo(
                         id=agent.id,
@@ -90,6 +138,7 @@ async def search_agents(
                         has_external_trigger=agent.has_external_trigger,
                         new_output=agent.new_output,
                         graph_id=agent.graph_id,
+                        inputs=input_schema,
                     )
                 )
         logger.info(f"Found {len(agents)} agents in {source}")
diff --git a/autogpt_platform/backend/backend/api/features/chat/tools/models.py b/autogpt_platform/backend/backend/api/features/chat/tools/models.py
index 8552681d03..49b6bdd48a 100644
--- a/autogpt_platform/backend/backend/api/features/chat/tools/models.py
+++ b/autogpt_platform/backend/backend/api/features/chat/tools/models.py
@@ -62,6 +62,10 @@ class AgentInfo(BaseModel):
     has_external_trigger: bool | None = None
     new_output: bool | None = None
     graph_id: str | None = None
+    inputs: dict[str, Any] | None = Field(
+        default=None,
+        description="Input schema for the agent, including field names, types, and defaults",
+    )
 
 
 class AgentsFoundResponse(ToolResponseBase):
diff --git a/autogpt_platform/backend/backend/api/features/chat/tools/run_agent.py b/autogpt_platform/backend/backend/api/features/chat/tools/run_agent.py
index a7fa65348a..cf26e94ff5 100644
--- a/autogpt_platform/backend/backend/api/features/chat/tools/run_agent.py
+++ b/autogpt_platform/backend/backend/api/features/chat/tools/run_agent.py
@@ -310,6 +310,26 @@ class RunAgentTool(BaseTool):
                     graph_version=graph.version,
                 )
 
+            # Check for unknown input fields - reject to prevent silent failures
+            valid_fields = set(input_properties.keys())
+            unknown_fields = provided_inputs - valid_fields
+            if unknown_fields:
+                credentials = extract_credentials_from_schema(
+                    graph.credentials_input_schema
+                )
+                return AgentDetailsResponse(
+                    message=(
+                        f"Unknown input field(s) provided: {', '.join(sorted(unknown_fields))}. "
+                        f"Agent was not executed. "
+                        f"Valid input fields are: {', '.join(sorted(valid_fields)) or 'none'}."
+                    ),
+                    session_id=session_id,
+                    agent=self._build_agent_details(graph, credentials),
+                    user_authenticated=True,
+                    graph_id=graph.id,
+                    graph_version=graph.version,
+                )
+
             # Step 4: Execute or Schedule
             if is_schedule:
                 return await self._schedule_agent(