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

Even though annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, the description adds valuable behavioral context: it makes an ACTIVE TCP connection, it is non-intrusive and connect-only, it does not authenticate or transfer data, and it is visible in target logs. It also discloses rate-limiting and the lack of an API key requirement. This goes well beyond the annotations and contains no contradiction.

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?

The description is front-loaded with purpose, then uses a labeled BEHAVIOR section, then alternatives, and then constraints. Every sentence adds information: what the probe does, what it does not do, visibility in logs, authorization, alternatives, rate limit, and return value. There is no filler or tautology.

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?

Given the output schema exists, return values do not need explanation. The description covers the tool's network behavior, safety profile, authorization boundaries, rate limits, API key requirements, and sibling tool routing. For a single-parameter tool with rich annotations and output schema, nothing significant is missing.

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?

The input schema already covers the only parameter (host) with a full description including accepted forms and authorization guidance, so schema coverage is 100%. The tool description does not add additional parameter-level meaning beyond the schema; it explains tool-level behavior but not new host semantics. Baseline 3 is appropriate when the schema carries the parameter documentation 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?

The description uses a specific verb ('Probe') with a clear resource ('a host for a fixed set of common TCP ports') and states the exact output: which ports are open, service name, and response time. It also distinguishes itself from sibling tools by naming ssl_check and http_security as alternatives for assessing service configuration, so an agent can tell them apart.

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 description explicitly says when to use this tool ('Use this to confirm which services are exposed') and names specific alternatives for different use cases ('Use ssl_check or http_security instead to assess a specific service's configuration'). It also states the authorization requirement, leaving no ambiguity about appropriate invocation.

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