Scan a live MCP server

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

Beyond readOnlyHint/openWorldHint/idempotentHint, the description adds the crucial behavioral fact that the scanned server's tools are never invoked, which tells the agent the remote target suffers no side effects. It also discloses network policy (public https only, env-var override for private networks) and enumerates the check categories performed, which the annotations cannot convey.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Three sentences, front-loaded with the action and scope, then the safety guarantee, then the endpoint restrictions. The parenthetical check list is dense but every item is decision-relevant; there is no filler.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a complex, network-touching scan tool with three parameters, full schema coverage and an output schema, the description covers what it does, what it touches, what it never does, and what it refuses. Return-value detail is correctly left to the output schema.

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

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

Schema description coverage is 100%, so url, fail_on and headers are already documented with types, defaults, an enum and a pattern. The description adds no extra meaning for fail_on thresholds or which headers matter (e.g. Authorization), so it sits at the baseline where the schema does the work.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description names specific verbs and resources: connect to a Streamable HTTP endpoint, enumerate tools/resources/prompts, run static rules and transport checks (TLS, auth, CORS, session handling). This is clearly a live-runtime scan, which separates it from siblings like scan_tools_export (export-based) and list_rules/explain_rule (rule metadata) without needing their schemas.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

It gives clear conditions for use (a live Streamable HTTP MCP endpoint) and explicit exclusions (local/private addresses refused unless MCP_GUARD_ALLOW_PRIVATE_NETWORK=1, https only). What's missing is explicit routing guidance such as when to prefer scan_tools_export over this for offline data, leaving the agent to infer the choice from sibling names.

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