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

Annotations already declare readOnlyHint=true with no destruction or open-world access, so the description builds on a covered safety profile. It adds genuinely non-obvious context: the response contains a plaintext password that should only be shown to the account owner, and a nonexistent or foreign plan_id yields an error result rather than empty data. It stops short of noting anything about password rotation or caching, which is why it isn't a 5.

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, no filler, and the payload (what fields are returned) is front-loaded before the routing rule and the secret-handling warning. Every clause carries information an agent would otherwise have to guess.

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 one-parameter read tool with annotations covering the safety profile, the description supplies the return contents, the alternative tool, the sensitive-data handling rule, and the error case. Nothing needed to select or invoke it correctly 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?

With one parameter at 100% schema coverage, the schema already carries the format and the pointer to list_plans as the source of the id. The description's note that a plan_id belonging to another account fails is useful, but it reads as access-control behavior rather than added meaning about the parameter itself, so baseline 3 holds.

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?

"Get full connection details for one plan" gives a specific verb and resource, then enumerates exactly what comes back (login, password, gateway host, HTTP/SOCKS5 ports, sticky-IP port range, remaining traffic). It also names the sibling it is not — get_proxy_lines — so the agent can separate the two without opening either 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?

Explicit selection rule: use this when you need credentials to configure a client yourself, use get_proxy_lines for ready-made proxy strings. That is a direct when-to-use plus a named alternative with the condition that selects it.

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