An agent tool manifest is a machine readable inventory of available page tools, their scope, and supporting metadata. In this pattern, the manifest is generated during build time so the agent sees the same content version as the published site. That reduces stale references and helps keep discovery consistent.
Expanded Definition
An agent tool manifest is the structured contract that tells an AI agent what tools exist, what each tool can do, what inputs it expects, and what metadata governs safe use. In agentic systems, the manifest sits between the model and the execution layer, so discovery is not based on ad hoc prompts or hidden runtime state but on a published inventory tied to a specific build.
That build-time binding matters because tool availability, permissions, and documentation can drift quickly in fast-moving environments. When the manifest is accurate, the agent can reason over a stable set of capabilities and operators can review exposure before deployment. This aligns closely with the intent of the OWASP Top 10 for Agentic Applications 2026 and the control-focus of the NIST AI Risk Management Framework, even though no single standard governs tool manifests yet. Definitions vary across vendors on whether the manifest is only descriptive or also policy-bearing.
The most common misapplication is treating the manifest as a convenience file rather than a governed interface, which occurs when teams let it diverge from the deployed tool surface after release.
Examples and Use Cases
Implementing agent tool manifests rigorously often introduces release coordination overhead, requiring organisations to weigh faster agent iteration against tighter control over what the agent can reach.
- A customer support agent is limited to read-only account lookup and ticket creation tools, with the manifest excluding billing actions until approval is granted.
- A software engineering agent uses a build-generated manifest so the tool list matches the published site version, reducing stale references and shadow capabilities.
- A data operations agent exposes only export, transform, and validation tools, while the manifest records required scopes and environmental constraints for each action.
- An organisation reviews the manifest alongside findings from the State of MCP Server Security 2025 because tool inventories often reveal missing access scoping before incidents do.
- Security teams compare the manifest to patterns described in the CoPhish OAuth Token Theft via Copilot Studio report and the Anthropic — first AI-orchestrated cyber espionage campaign report to spot tool exposure that could be abused through prompt manipulation or tool chaining.
Why It Matters in NHI Security
Agent tool manifests are a control point for non-human identity governance because they determine which identities, tokens, and execution paths are even reachable by an agent. When manifests are incomplete or stale, teams lose visibility into tool scope, and that makes least privilege, approval workflows, and auditability much harder to enforce. NHI Mgmt Group research shows that 96% of organisations store secrets outside secrets managers in vulnerable locations, including code and configuration files, which means manifest hygiene often intersects directly with secret exposure and access sprawl.
This is especially important for agents that interact with MCP servers, where the manifest may be the only practical boundary between a model and a credential-bearing tool. The OWASP NHI Top 10 and the Ultimate Guide to NHIs — 2025 Outlook and Predictions both reinforce that visibility and offboarding are inseparable from secure identity operations, while the NIST AI Risk Management Framework and CSA MAESTRO agentic AI threat modeling framework both support governance that keeps agent actions aligned to defined intent.
Organisations typically encounter manifest drift only after an agent accesses a tool it should no longer have, at which point the agent tool manifest becomes operationally unavoidable to address.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
OWASP Non-Human Identity Top 10, OWASP Agentic AI Top 10 and CSA MAESTRO address the attack and risk surface, while NIST AI RMF and NIST Zero Trust (SP 800-207) set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| OWASP Non-Human Identity Top 10 | NHI-02 | Tool manifests expose scoped access boundaries and hidden NHI reach. |
| OWASP Agentic AI Top 10 | A3 | Agent tool access and misuse are core agentic application security concerns. |
| NIST AI RMF | AI RMF addresses governance, transparency, and accountability for AI system behavior. | |
| NIST Zero Trust (SP 800-207) | SC-7 | Zero trust requires explicit, continuously evaluated access boundaries. |
| CSA MAESTRO | MAESTRO models agent action surfaces, tool use, and orchestration risk. |
Treat the manifest as a governed artifact and test it for accuracy, traceability, and change control.
