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describe_instance_policy

Retrieve an instance's data policy before your first store to learn entity scope, write requirements, and sensitivity limits. Avoid rejected writes by reading enforcement rules up front.

Instructions

Return this instance's data policy: what it is for (purpose), which entity types are in scope (in_scope_entity_types) or explicitly out of scope (out_of_scope_entity_types), whether person-data writes require a lawful-basis tag or provenance metadata, and the maximum field sensitivity class it will hold. Call this at the start of a session against an unfamiliar or shared instance, before your first store, so your writes comply instead of being rejected — policy discovered by trial-and-error rejection is strictly worse than reading it up front. Response shape is {"policy": <object|null>, "entity_id": <string|null>}. Returns {"policy": null, "entity_id": null} when the instance declares no policy; that means unrestricted, NOT deny-all. entity_id is an opaque identifier — pass it to correct() when authoring/updating the policy remotely rather than re-deriving or guessing it. When enforcement is "enforced", violating store/correct calls are rejected with ERR_STORE_POLICY_DENIED and nothing in the request is persisted; when "advisory", violating writes are accepted but you are still expected to comply. Takes no arguments: the policy is instance-wide, identical for every caller. Read-only; no persistence side effects.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault

No arguments

Schema Changelog

Changes observed during successful MCP inspections.

  1. Addedv0.21.5

TDQS

A4.9/5.0
Behavior5/5

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

No annotations are provided, so the description carries the full burden; it exceeds it by stating read-only/no persistence side effects, instance-wide scope, no arguments, response shape, null semantics, and exact behavior for 'enforced' vs 'advisory' modes. It also warns that violating calls are rejected and nothing is persisted.

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 first sentence front-loads the core return value, followed by usage timing, response shape, edge-case semantics, and enforcement behavior. Despite its length, every sentence adds distinct value; there is no wasted or redundant wording.

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 no output schema and no annotations, the description must explain return values and safety, and it does so fully: response shape, null-policy interpretation, entity_id handling for correct(), enforcement consequences, and read-only nature. This is sufficient for an agent to decide when and how to invoke it.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

There are zero parameters, so the baseline is 4; the description reinforces this with 'Takes no arguments: the policy is instance-wide, identical for every caller,' which explains why the schema is empty and removes any temptation to supply caller-specific arguments.

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 opens with a specific verb and resource: 'Return this instance's data policy' and enumerates exactly which aspects are covered (purpose, scopes, write requirements, max sensitivity class). It clearly distinguishes itself from siblings like store/correct/describe_entity_type by framing it as the session-start introspection call.

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?

Explicitly instructs when to call: 'at the start of a session against an unfamiliar or shared instance, before your first store' and gives a reason. It also defines what null policy means (unrestricted, not deny-all) and how to interpret enforcement modes, making the use decision clear.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.