Struct Capability 

pub struct Capability {
    pub name: &'static str,
    pub main_denial: Option<&'static str>,
    pub summary: &'static str,
    pub filter_fields: &'static [FilterField],
    pub example_filter: &'static str,
}

One gated capability and the policy filter: surface it exposes.

Fields

name: &'static str

The name passed to check() — exactly what a policy rule’s capability: must equal (capability names are matched verbatim).

main_denial: Option<&'static str>

Why the runtime refuses this capability to main outright, ahead of the policy engine — None for an ordinary capability a rule can grant to any caller. A rule granting a marked capability to main is dead, so the surfaces that scaffold, add, and lint rules read this one fact rather than each restating the carve-out, and each shows the reason verbatim.

summary: &'static str

One-line description of what gating the capability controls.

filter_fields: &'static [FilterField]

Context fields a filter: expression can match on, as supplied by a representative call. Documents what a rule can constrain.

example_filter: &'static str

A ready-to-uncomment example filter: expression for the scaffold.

Implementations

impl Capability

pub fn is_template(&self) -> bool

Whether the name is a template (mcp.<server>) rather than a concrete name a policy rule can use verbatim.

pub fn grantable_to_main(&self) -> bool

Whether a policy rule granting this capability to main can take effect.

pub fn field_names(&self) -> impl Iterator<Item = &'static str>

The filter fields’ names, for surfaces that don’t show types.