session_info

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

With no annotations, the description must carry the behavioral burden. 'Session observability' and the named fields strongly imply a read-only diagnostic endpoint, but the description does not explicitly state that it is read-only, what permissions are required, or whether any side effects occur. It adds useful context about observing re-login but stops short of full behavioral disclosure.

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 front-loaded sentence with no wasted words. The key concept (session observability) and the concrete fields are presented immediately, followed by the practical benefit.

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 tool has no parameters and an output schema exists, the description does not need to explain return values in detail. It provides enough context to understand why an agent would call this tool, though it could explicitly confirm read-only safety in the absence of annotations.

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 tool has zero parameters, so the baseline is 4. The description names three output fields, which is helpful even though the output schema already documents them.

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 clearly identifies the resource as session observability and names the concrete fields returned (age_seconds, login_count, stok_prefix). It lacks an explicit verb like 'return' but makes the tool's purpose unambiguous, especially given no sibling tool covers sessions.

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 'lets you see the auto-recovery (re-login) happen instead of trusting it silently' implies a debugging/monitoring use case. However, there is no explicit when-to-use guidance, no when-not-to-use guidance, and no named alternative to compare against.

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