Interface: AgentSpec<TConfig>
Defined in: core/agentSpec.ts:79
Everything actually about the domain that buildSessionOptions() needs but doesn't
decide itself: which system prompt to build, which MCP servers to talk to besides the
generic human-in-the-loop/knowledge ones this kit already wires up, which local plugin
roots (skills/commands) to load, and which opt-in subagents (if any) to register.
Deliberately not named AgentDefinition: the SDK already uses that name for a single
subagent's own definition (Options.agents: Record<string, AgentDefinition>), and this
is a level above that — it's what decides which subagents get registered, among other
things.
Type Parameters
| Type Parameter |
|---|
TConfig extends BaseSessionConfig |
Properties
| Property | Type | Description | Defined in |
|---|---|---|---|
disallowedTools? | string[] | Tool names to explicitly block regardless of what canUseTool/allowAnyMcpTool would otherwise allow (e.g. a browser-automation agent blocking "mcp__playwright__browser_run_code_unsafe", which Microsoft's own description calls RCE-equivalent). Confirmed empirically that disallowedTools takes full precedence over a permissive canUseTool — a disallowed tool never even reaches that callback. | core/agentSpec.ts:130 |
helpGuide? | string | Absolute path of a markdown guide to the agent's own domain (its commands, configuration, folders), which the agent-help skill includes. Only with identity. | core/agentSpec.ts:94 |
humanApprovalTexts? | object | Text for the generic human-approval checkpoint (see tools/humanApproval.ts) — what counts as "publishing something visible to others" is entirely domain-specific. Omit to use this kit's own generic, domain-neutral defaults. | core/agentSpec.ts:190 |
humanApprovalTexts.approved | string | - | core/agentSpec.ts:190 |
humanApprovalTexts.description | string | - | core/agentSpec.ts:190 |
humanApprovalTexts.rejected | string | - | core/agentSpec.ts:190 |
identity? | AgentIdentity | Who the agent is. With it, the kit tells the model its name, version and what it is, plus agent-kit's version, and offers the agent-help skill, which answers how to use the agent: the kit's chat (modes, keys, slash commands, resuming) and helpGuide. Without it, neither. | core/agentSpec.ts:89 |
knowledgeBase? | boolean | The built-in knowledge base (see knowledge.ts): when config.knowledgeDir is set, the kit appends its "Knowledge base" rules to the system prompt, loads its plugin (skills knowledge-ingest/knowledge-query/knowledge-lint, commands /knowledge:ingest, /knowledge:query, /knowledge:lint) and its knowledge_* tools, the only way into the knowledge base (ADR-024). On by default; false makes knowledgeDir a folder of the agent's own notes, kept with the file tools under rules it writes itself. | core/agentSpec.ts:143 |
knowledgePageTypes? | PageType[] | The agent's own page types for the built-in knowledge base, besides the kit's (summary, concept, entity, synthesis): each with its folder ("" for the root), index section, description (told to the model) and template. | core/agentSpec.ts:149 |
manualInterventionTexts? | object | Text for the generic manual-intervention checkpoint (see tools/manualLogin.ts), AND this domain's opt-in signal for offering that checkpoint at all: buildSessionOptions() only registers request_manual_login when this is set (and mode !== "autonomous"). Manual intervention only makes sense for a domain that drives some live UI a human could actually step into by hand (a browser window, say) — there's no generic default to fall back to the way there is for humanApprovalTexts above, because this kit can't assume every agent built on it has such a UI at all. Leave unset for a domain that doesn't. | core/agentSpec.ts:201 |
manualInterventionTexts.checkpointLines | string[] | - | core/agentSpec.ts:205 |
manualInterventionTexts.checkpointQuestion? | string | - | core/agentSpec.ts:206 |
manualInterventionTexts.checkpointTitle | string | - | core/agentSpec.ts:204 |
manualInterventionTexts.confirmedMessage | string | - | core/agentSpec.ts:203 |
manualInterventionTexts.toolDescription | string | - | core/agentSpec.ts:202 |
planMode? | PlanModeSpec<TConfig> | What the agent may still do in "plan" mode, where it only reads and plans (see hooks/planGate.ts). Without it, the agent can read, search, ask a human and delegate, writes nothing and presents its plan in its reply. | core/agentSpec.ts:214 |
replyInLanguage? | boolean | Whether the kit tells the agent (and each subagent) to reply in the resolved language (config.language, --language, the system's), following the human if they write in another one. On by default; false leaves the reply language to the agent's own prompt. | core/agentSpec.ts:161 |
saveToSourcesDescription? | string | Overrides this kit's generic save_to_sources tool description (registered whenever config.sourcesDir is set) with domain-specific wording. | core/agentSpec.ts:133 |
settingSources? | SettingSource[] | Which filesystem settings the session loads (the SDK's settingSources): "project" is the project's .claude/ (settings, skills, commands) and its CLAUDE.md files, "local" its .claude/settings.local.json, "user" the runner's own ~/.claude/ (settings, CLAUDE.md, skills). Default ["project"]: the runner's personal Claude Code configuration (its language, output style, CLAUDE.md, hooks...) never reaches the agent unless asked for with "user" — the SDK's own default loads all three, and the runner's language setting then outranked the agent's prompt. [] isolates the agent from every settings file, CLAUDE.md included. | core/agentSpec.ts:173 |
skills? | string[] | "all" | "plugins" | The skills the agent offers (the SDK's skills): names, or plugin:skill for a plugin's. Default "all", every skill found: the SDK's own (about twenty, whatever settingSources says), the project's, the plugins'. "plugins" offers only those of the plugins the session loads (pluginRoots, the knowledge base's, agent-help's), without naming them. A list keeps the rest out of each turn's context; the knowledge base's own skills are added to it when the knowledge base is on. A context filter, not a sandbox. | core/agentSpec.ts:183 |
Methods
buildMcpServers()
buildMcpServers(config, runDir): Record<string, McpServerConfig>;
Defined in: core/agentSpec.ts:104
MCP servers this agent always registers (e.g. Playwright for a browser-driving
agent), on top of the generic ones buildSessionOptions() wires up itself when
applicable (human approval, manual intervention, save-to-knowledge) — those aren't
part of the spec because they're driven by mode plus this spec's own
manualInterventionTexts/knowledgeDir/sourcesDir, not by anything else
domain-specific.
Parameters
| Parameter | Type |
|---|---|
config | TConfig |
runDir | string |
Returns
Record<string, McpServerConfig>
buildSubagents()
buildSubagents(config):
| {
agents: Record<string, SdkSubagentDefinition>;
allowedSubagentTypes: string[];
}
| undefined;
Defined in: core/agentSpec.ts:121
Opt-in subagents (the SDK's Options.agents) this spec wants registered for this
config, plus which subagent_type values are therefore allowed to be spawned via the
Agent tool (see hooks/subagentTypeGate.ts — the SDK's own built-in
"general-purpose" type is always spawnable regardless of this list, which is exactly
why that gate exists). Returns undefined when this config needs no subagents at
all, so buildSessionOptions() knows not to grant Agent/Bash in the first place.
Parameters
| Parameter | Type |
|---|---|
config | TConfig |
Returns
| {
agents: Record<string, SdkSubagentDefinition>;
allowedSubagentTypes: string[];
}
| undefined
buildSystemPrompt()
buildSystemPrompt(config): string;
Defined in: core/agentSpec.ts:81
The system prompt for this run — everything role/mode/domain-specific lives behind this call.
Parameters
| Parameter | Type |
|---|---|
config | TConfig |
Returns
string
knowledgeStore()?
optional knowledgeStore(config): KnowledgeStore;
Defined in: core/agentSpec.ts:154
The knowledge base's store, instead of the kit's over markdown files in knowledgeDir
(e.g. a database or a vector store implementing KnowledgeStore).
Parameters
| Parameter | Type |
|---|---|
config | TConfig |
Returns
pluginRoots()
pluginRoots(config): string[];
Defined in: core/agentSpec.ts:111
Local plugin roots (skills/commands, SDK "local" plugin type) to load, in the order
given, when the session has file tools (config.knowledgeDir/config.sourcesDir). Absolute paths; buildSessionOptions()
doesn't know or care where they live on disk.
Parameters
| Parameter | Type |
|---|---|
config | TConfig |
Returns
string[]