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

Annotations already declare readOnlyHint/idempotentHint/openWorldHint, yet the description still adds real substance: it discloses the exact probe depth (initialize + tools/list, no tool invocation), outbound network behavior, and the cost model (free 10 checks/day per IP, then $0.005 via x402 or credits). The https-only restriction and the emitted report contents are behavior an agent cannot infer from the annotations.

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?

Front-loaded with the decisive question, then the method, then constraints and pricing — a sensible order. It is dense and slightly list-like in the middle ('reachability, protocol version, sign-in method, x402 payment terms...'), but each clause carries information an agent would otherwise have to discover by calling the tool.

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?

There is no output schema, so the description must describe the return payload, and it does: reachability, protocol version, auth method, payment terms, latency, tool count, token cost, compatibility, poisoning findings, grade A-F, and a reusable pin. Combined with the rate-limit and host constraints, an agent has everything needed to decide to call it and interpret the result.

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?

Only one parameter and schema description coverage is 100%, with the schema itself explaining Streamable HTTP, https, and giving an example URL. The description echoes the https public-host constraint but adds no format, encoding, or validation detail beyond the schema. Baseline 3 is appropriate when the schema carries the parameter burden.

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?

Opens with a specific decision question ('Does this remote MCP server work, and is it worth connecting or paying for?') and immediately names the concrete method: sends initialize and tools/list. The scope (reachability, protocol version, auth, payment terms, latency, tool count, poisoning, grade, pin) is specific enough to distinguish it from audit_tools, diff_tools and watch_mcp_server without opening any schema.

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?

The lead question establishes the use case (pre-connect / pre-purchase evaluation) and 'sends initialize and tools/list only (never calls a tool)' sets a clear boundary on what the check does. It also states the eligibility constraint (https public hosts only). It never explicitly names when to reach for watch_mcp_server or diff_tools instead, so the sibling routing is implied rather than stated.

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