login_from_session

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

No annotations are provided, so the description carries the full burden. It states the tool creates an instance but gives no indication of side effects, auth checks, error behavior on an invalid/expired cookie, or whether any remote calls are made. For an authentication-related tool this is a significant transparency gap.

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?

A single sentence that names the action and source. It is front-loaded and economical, though the brevity comes at the cost of behavioral and parameter detail.

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?

With three required parameters, zero annotations, and no output schema, the description is too thin. An agent needs to know what the returned instance supports, how session validity is handled, and what format subdomain/username must take.

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 0%, so the description must explain the parameters itself. It only identifies session_id as an existing PHPSESSID cookie; the role of username and subdomain is left unexplained, which is particularly important for a login tool.

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 states a specific action ('Create a logged-in Edupage instance') and identifies the source ('existing PHPSESSID cookie'), which clearly differentiates it from credential-based login tools. However, it doesn't explicitly name siblings or say why this tool exists over alternatives.

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 phrase 'from an existing PHPSESSID cookie' provides clear usage context: use this when you already have a session cookie rather than credentials. It does not explicitly state when not to use it or mention alternatives like login, but the condition is reasonably clear.

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