feat(cluster-agent): Implement MCP Server with Leader Election tool

[wdhif]

What does this PR do?

Implements a basic MCP (Model Context Protocol) server within the Datadog Cluster Agent that exposes Cluster Agent leadership information through a standardized tool interface.

Motivation

The MCP server enables external tools and AI assistants to programmatically query cluster agent leadership information through a standardized protocol. This improves observability and debugging capabilities for multi-replica cluster agent deployments where understanding leadership status is crucial for troubleshooting.

Describe how you validated your changes

Screen.Recording.2025-12-03.at.18.23.10.mov

Additional Notes

No changelog was created, as the current Leader Election tool is only used for testing purposes. Future changelogs will be added once other tool implementations is in place.

[agent-platform-auto-pr]

Go Package Import Differences

Baseline: 4830ea9
Comparison: 4d5ffb1

binary	os	arch	change
cluster-agent	linux	amd64	+7, -0 +github.com/DataDog/datadog-agent/pkg/clusteragent/mcp +github.com/DataDog/datadog-agent/pkg/clusteragent/mcp/tools +github.com/google/jsonschema-go/jsonschema +github.com/modelcontextprotocol/go-sdk/auth +github.com/modelcontextprotocol/go-sdk/jsonrpc +github.com/modelcontextprotocol/go-sdk/mcp +github.com/yosida95/uritemplate/v3
cluster-agent	linux	arm64	+7, -0 +github.com/DataDog/datadog-agent/pkg/clusteragent/mcp +github.com/DataDog/datadog-agent/pkg/clusteragent/mcp/tools +github.com/google/jsonschema-go/jsonschema +github.com/modelcontextprotocol/go-sdk/auth +github.com/modelcontextprotocol/go-sdk/jsonrpc +github.com/modelcontextprotocol/go-sdk/mcp +github.com/yosida95/uritemplate/v3

[agent-platform-auto-pr]

Static quality checks

❌ Please find below the results from static quality gates
Comparison made with ancestor 4830ea9

Error

	Quality gate	Delta	On disk size (MiB)	Delta	On wire size (MiB)
❌	docker_cluster_agent_amd64	$${+0.9}$$	$${179.78}$$ > $${179.28}$$	$${+0.26}$$	$${63.43}$$ < $${63.96}$$
❌	docker_cluster_agent_arm64	$${+0.88}$$	$${197.27}$$ > $${196.79}$$	$${+0.25}$$	$${60.15}$$ < $${60.69}$$

Gate failure full details

Quality gate	Error type	Error message
docker_cluster_agent_amd64	StaticQualityGateFailed	�[91mstatic_quality_gate_docker_cluster_agent_amd64 failed! Disk size 179.8 MB exceeds limit of 179.3 MB by 0.5 MB�[0m
docker_cluster_agent_arm64	StaticQualityGateFailed	�[91mstatic_quality_gate_docker_cluster_agent_arm64 failed! Disk size 197.3 MB exceeds limit of 196.8 MB by 0.5 MB�[0m

Static quality gates prevent the PR to merge!
You can check the static quality gates confluence page for guidance. We also have a toolbox page available to list tools useful to debug the size increase.

Successful checks

Info

	Quality gate	Delta	On disk size (MiB)	Delta	On wire size (MiB)
✅	agent_deb_amd64	$${+0}$$	$${705.41}$$ < $${706.32}$$	$${-0.01}$$	$${172.92}$$ < $${173.81}$$
✅	agent_deb_amd64_fips	$${+0.01}$$	$${700.26}$$ < $${701.16}$$	$${-0.04}$$	$${171.77}$$ < $${172.71}$$
✅	agent_heroku_amd64	$${+0}$$	$${327.43}$$ < $${327.69}$$	$${+0.01}$$	$${87.37}$$ < $${88.19}$$
✅	agent_msi	$${+0}$$	$${979.24}$$ < $${982.08}$$	$${-0.04}$$	$${141.83}$$ < $${143.01}$$
✅	agent_rpm_amd64	$${+0}$$	$${705.4}$$ < $${706.31}$$	$${-0.01}$$	$${175.98}$$ < $${176.86}$$
✅	agent_rpm_amd64_fips	$${+0.01}$$	$${700.24}$$ < $${701.15}$$	$${+0.03}$$	$${174.1}$$ < $${174.95}$$
✅	agent_rpm_arm64	$${+0.01}$$	$${691.08}$$ < $${691.67}$$	$${-0.04}$$	$${159.78}$$ < $${160.7}$$
✅	agent_rpm_arm64_fips	$${+0}$$	$${686.89}$$ < $${687.54}$$	$${+0.02}$$	$${159.18}$$ < $${160.1}$$
✅	agent_suse_amd64	$${+0}$$	$${705.4}$$ < $${706.31}$$	$${-0.01}$$	$${175.98}$$ < $${176.86}$$
✅	agent_suse_amd64_fips	$${+0.01}$$	$${700.24}$$ < $${701.15}$$	$${+0.03}$$	$${174.1}$$ < $${174.95}$$
✅	agent_suse_arm64	$${+0.01}$$	$${691.08}$$ < $${691.67}$$	$${-0.04}$$	$${159.78}$$ < $${160.7}$$
✅	agent_suse_arm64_fips	$${+0}$$	$${686.89}$$ < $${687.54}$$	$${+0.02}$$	$${159.18}$$ < $${160.1}$$
✅	docker_agent_amd64	$${+0}$$	$${767.74}$$ < $${768.66}$$	$${-0}$$	$${260.67}$$ < $${261.52}$$
✅	docker_agent_arm64	$${+0.01}$$	$${777.7}$$ < $${778.35}$$	$${+0}$$	$${250.86}$$ < $${251.72}$$
✅	docker_agent_jmx_amd64	$${+0}$$	$${958.62}$$ < $${959.54}$$	$${-0}$$	$${329.31}$$ < $${330.15}$$
✅	docker_agent_jmx_arm64	$${+0.01}$$	$${957.3}$$ < $${957.95}$$	$${-0}$$	$${315.48}$$ < $${316.35}$$
✅	docker_cws_instrumentation_amd64	$${+0}$$	$${7.07}$$ < $${7.12}$$	$${+0}$$	$${2.95}$$ < $${3.29}$$
✅	docker_cws_instrumentation_arm64	$${0}$$	$${6.69}$$ < $${6.92}$$	$${-0}$$	$${2.7}$$ < $${3.07}$$
✅	docker_dogstatsd_amd64	$${-0}$$	$${38.66}$$ < $${39.3}$$	$${+0}$$	$${14.93}$$ < $${15.76}$$
✅	docker_dogstatsd_arm64	$${+0.06}$$	$${37.36}$$ < $${37.94}$$	$${-0}$$	$${14.38}$$ < $${14.83}$$
✅	dogstatsd_deb_amd64	$${0}$$	$${29.88}$$ < $${30.53}$$	$${-0}$$	$${7.88}$$ < $${8.75}$$
✅	dogstatsd_deb_arm64	$${0}$$	$${28.39}$$ < $${29.11}$$	$${-0}$$	$${6.82}$$ < $${7.71}$$
✅	dogstatsd_rpm_amd64	$${0}$$	$${29.88}$$ < $${30.53}$$	$${-0}$$	$${7.89}$$ < $${8.76}$$
✅	dogstatsd_suse_amd64	$${0}$$	$${29.88}$$ < $${30.53}$$	$${-0}$$	$${7.89}$$ < $${8.76}$$
✅	iot_agent_deb_amd64	$${+0}$$	$${42.6}$$ < $${43.19}$$	$${-0}$$	$${11.12}$$ < $${11.98}$$
✅	iot_agent_deb_arm64	$${0}$$	$${40.34}$$ < $${40.92}$$	$${-0}$$	$${9.58}$$ < $${10.45}$$
✅	iot_agent_deb_armhf	$${0}$$	$${40.24}$$ < $${40.86}$$	$${+0}$$	$${9.7}$$ < $${10.56}$$
✅	iot_agent_rpm_amd64	$${+0}$$	$${42.6}$$ < $${43.19}$$	$${+0}$$	$${11.14}$$ < $${12.0}$$
✅	iot_agent_suse_amd64	$${+0}$$	$${42.6}$$ < $${43.19}$$	$${+0}$$	$${11.14}$$ < $${12.0}$$

[cit-pr-commenter]

Regression Detector

Regression Detector Results

Metrics dashboard
Target profiles
Run ID: 6b27fb19-1710-4228-814e-b60685e4df0e

Baseline: 4830ea9
Comparison: 4d5ffb1
Diff

Optimization Goals: ✅ No significant changes detected

Experiments ignored for regressions

Regressions in experiments with settings containing erratic: true are ignored.

perf	experiment	goal	Δ mean %	Δ mean % CI	trials	links
➖	docker_containers_cpu	% cpu utilization	+0.43	[-2.60, +3.46]	1	Logs

Fine details of change detection per experiment

perf	experiment	goal	Δ mean %	Δ mean % CI	trials	links
➖	quality_gate_logs	% cpu utilization	+1.39	[-0.08, +2.86]	1	Logs bounds checks dashboard
➖	quality_gate_metrics_logs	memory utilization	+1.32	[+1.10, +1.53]	1	Logs bounds checks dashboard
➖	ddot_metrics	memory utilization	+1.01	[+0.78, +1.24]	1	Logs
➖	docker_containers_cpu	% cpu utilization	+0.43	[-2.60, +3.46]	1	Logs
➖	docker_containers_memory	memory utilization	+0.37	[+0.30, +0.44]	1	Logs
➖	otlp_ingest_metrics	memory utilization	+0.34	[+0.20, +0.49]	1	Logs
➖	ddot_logs	memory utilization	+0.32	[+0.26, +0.38]	1	Logs
➖	ddot_metrics_sum_cumulative	memory utilization	+0.26	[+0.09, +0.43]	1	Logs
➖	file_tree	memory utilization	+0.21	[+0.16, +0.27]	1	Logs
➖	uds_dogstatsd_20mb_12k_contexts_20_senders	memory utilization	+0.18	[+0.12, +0.24]	1	Logs
➖	quality_gate_idle	memory utilization	+0.11	[+0.07, +0.16]	1	Logs bounds checks dashboard
➖	ddot_metrics_sum_delta	memory utilization	+0.10	[-0.11, +0.32]	1	Logs
➖	file_to_blackhole_0ms_latency	egress throughput	+0.06	[-0.33, +0.46]	1	Logs
➖	tcp_dd_logs_filter_exclude	ingress throughput	+0.00	[-0.08, +0.08]	1	Logs
➖	uds_dogstatsd_to_api	ingress throughput	-0.01	[-0.13, +0.12]	1	Logs
➖	uds_dogstatsd_to_api_v3	ingress throughput	-0.01	[-0.14, +0.13]	1	Logs
➖	file_to_blackhole_500ms_latency	egress throughput	-0.02	[-0.40, +0.35]	1	Logs
➖	file_to_blackhole_100ms_latency	egress throughput	-0.04	[-0.09, -0.00]	1	Logs
➖	file_to_blackhole_1000ms_latency	egress throughput	-0.05	[-0.46, +0.36]	1	Logs
➖	ddot_metrics_sum_cumulativetodelta_exporter	memory utilization	-0.11	[-0.35, +0.12]	1	Logs
➖	quality_gate_idle_all_features	memory utilization	-0.25	[-0.28, -0.21]	1	Logs bounds checks dashboard
➖	tcp_syslog_to_blackhole	ingress throughput	-0.66	[-0.75, -0.58]	1	Logs
➖	otlp_ingest_logs	memory utilization	-1.26	[-1.36, -1.16]	1	Logs

Bounds Checks: ✅ Passed

perf	experiment	bounds_check_name	replicates_passed	links
✅	docker_containers_cpu	simple_check_run	10/10
✅	docker_containers_memory	memory_usage	10/10
✅	docker_containers_memory	simple_check_run	10/10
✅	file_to_blackhole_0ms_latency	lost_bytes	10/10
✅	file_to_blackhole_0ms_latency	memory_usage	10/10
✅	file_to_blackhole_1000ms_latency	lost_bytes	10/10
✅	file_to_blackhole_1000ms_latency	memory_usage	10/10
✅	file_to_blackhole_100ms_latency	lost_bytes	10/10
✅	file_to_blackhole_100ms_latency	memory_usage	10/10
✅	file_to_blackhole_500ms_latency	lost_bytes	10/10
✅	file_to_blackhole_500ms_latency	memory_usage	10/10
✅	quality_gate_idle	intake_connections	10/10	bounds checks dashboard
✅	quality_gate_idle	memory_usage	10/10	bounds checks dashboard
✅	quality_gate_idle_all_features	intake_connections	10/10	bounds checks dashboard
✅	quality_gate_idle_all_features	memory_usage	10/10	bounds checks dashboard
✅	quality_gate_logs	intake_connections	10/10	bounds checks dashboard
✅	quality_gate_logs	lost_bytes	10/10	bounds checks dashboard
✅	quality_gate_logs	memory_usage	10/10	bounds checks dashboard
✅	quality_gate_metrics_logs	cpu_usage	10/10	bounds checks dashboard
✅	quality_gate_metrics_logs	intake_connections	10/10	bounds checks dashboard
✅	quality_gate_metrics_logs	lost_bytes	10/10	bounds checks dashboard
✅	quality_gate_metrics_logs	memory_usage	10/10	bounds checks dashboard

Explanation

Confidence level: 90.00%
Effect size tolerance: |Δ mean %| ≥ 5.00%

Performance changes are noted in the perf column of each table:

• ✅ = significantly better comparison variant performance
• ❌ = significantly worse comparison variant performance
• ➖ = no significant change in performance

A regression test is an A/B test of target performance in a repeatable rig, where "performance" is measured as "comparison variant minus baseline variant" for an optimization goal (e.g., ingress throughput). Due to intrinsic variability in measuring that goal, we can only estimate its mean value for each experiment; we report uncertainty in that value as a 90.00% confidence interval denoted "Δ mean % CI".

For each experiment, we decide whether a change in performance is a "regression" -- a change worth investigating further -- if all of the following criteria are true:

1. Its estimated |Δ mean %| ≥ 5.00%, indicating the change is big enough to merit a closer look.

2. Its 90.00% confidence interval "Δ mean % CI" does not contain zero, indicating that if our statistical model is accurate, there is at least a 90.00% chance there is a difference in performance between baseline and comparison variants.

3. Its configuration does not mark it "erratic".

CI Pass/Fail Decision

✅ Passed. All Quality Gates passed.

• quality_gate_metrics_logs, bounds check lost_bytes: 10/10 replicas passed. Gate passed.
• quality_gate_metrics_logs, bounds check memory_usage: 10/10 replicas passed. Gate passed.
• quality_gate_metrics_logs, bounds check cpu_usage: 10/10 replicas passed. Gate passed.
• quality_gate_metrics_logs, bounds check intake_connections: 10/10 replicas passed. Gate passed.
• quality_gate_idle_all_features, bounds check memory_usage: 10/10 replicas passed. Gate passed.
• quality_gate_idle_all_features, bounds check intake_connections: 10/10 replicas passed. Gate passed.
• quality_gate_idle, bounds check memory_usage: 10/10 replicas passed. Gate passed.
• quality_gate_idle, bounds check intake_connections: 10/10 replicas passed. Gate passed.
• quality_gate_logs, bounds check lost_bytes: 10/10 replicas passed. Gate passed.
• quality_gate_logs, bounds check memory_usage: 10/10 replicas passed. Gate passed.
• quality_gate_logs, bounds check intake_connections: 10/10 replicas passed. Gate passed.