Companies adopt Model Context Protocol scoping to reduce AI agent token costs

To address the rising token costs of AI agents, companies are adopting Model Context Protocol (MCP) scoping. Okta proposes identity-based filtering to restrict the tools exposed to an agent, which its internal modeling shows can reduce visible tools and schema token costs by over 90%. Meanwhile, Fieldguide launches Fieldguide MCP on August 12, 2026, to connect live engagement data directly to AI tools like Claude and Copilot, allowing practitioners to manage audits using plain language.

MCP tool scoping costs

• ▪Okta's internal modeling found that identity-based scoping of Model Context Protocol tool lists reduced the number of visible tools by more than 90% in some scenarios.
• ▪Okta's internal modeling of Model Context Protocol tool scoping showed that tool-schema token costs fell by roughly 90%, tracking tool-count reduction nearly linearly.
• ▪Okta's internal modeling for Model Context Protocol tool scoping was based on Okta product data and public vendor documentation, with no customer data used.

AI agent token overhead

• ▪Model Context Protocol servers connect AI agents to tools, but the AI model receives a representation of every available tool in its prompt on every turn, creating prompt overhead.
• ▪Okta states that prompt overhead costs are incurred before an AI agent attempts a tool call, meaning a runtime rejection of an unauthorized request cannot recover consumed tokens.
• ▪Okta's internal modeling of Model Context Protocol tool scoping mapped tools to OAuth scopes and defined representative user segments, such as helpdesk operators and administrators, to estimate scoped exposure.

Okta identity-based filtering

• ▪Okta's proposed identity-based control filters the list of Model Context Protocol tools before it reaches the AI model, using permissions assigned to an agent identity and its associated user.
• ▪Paul Webber, Principal Cybersecurity Industry Analyst at Software Analyst Cyber Research, stated that cost control for AI agents is best provided using identity governance tools.
• ▪Okta's identity-based scoping checks tool access at two points: when the tool list is assembled for the agent prompt, and when the agent attempts to execute a tool call.

Fieldguide MCP product launch

• ▪Fieldguide MCP, which has been rolling out to customers since July 2026, allows practitioners to query engagement status and perform routine actions using plain language.
• ▪Fieldguide launched Fieldguide MCP on August 12, 2026, to connect live engagement data directly into AI tools like Claude, Copilot, and Gemini.
• ▪Alongside Fieldguide MCP, Fieldguide introduced Field Financials, a tool featuring three coordinated agents to automate financial audit engagement tasks.

Tool schema prompt taxation

• ▪The 'tool tax' cost compounds when a widely used Model Context Protocol server exposes many tools, as each active user incurs prompt overhead on every model call.
• ▪Okta refers to the prompt overhead caused by exposing Model Context Protocol tool schemas, names, descriptions, and parameters to an AI model as the 'tool tax.'