Auth status

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

The annotation readOnlyHint=true already indicates a safe read, and the description adds a valuable guarantee: 'Never returns secrets.' This goes beyond the annotation by explicitly reassuring the agent about data sensitivity, which is relevant for a tool that shows an email. No contradiction with 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?

A single sentence conveys the core functionality and a critical safety guarantee. Every word earns its place; the 'Never returns secrets' clause is front-loaded but follows naturally. No fluff or redundancy.

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?

The description is fully sufficient for a zero-parameter, read-only status tool. The output schema (present but not shown) presumably documents return fields like sessionExists and email. The description covers what it does and a behavioral guarantee, leaving no ambiguity for an agent to call it correctly.

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 there is nothing to document beyond the schema. The description effectively communicates what the tool returns (session existence and email), giving the agent meaningful context that the empty schema cannot. With no parameters to clarify, the description carries the full semantic burden and does so well.

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 states the tool's purpose: 'Show whether a local Benepass session exists, and the logged-in email.' This is a specific verb (show) and resource (local Benepass session) that distinguishes it from sibling tools like start_login, complete_login, and logout, which handle authentication state transitions rather than inspection.

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 implies usage as a status check but does not explicitly state when to use it versus alternatives, nor any exclusions. For instance, it doesn't say 'use this before calling other authenticated endpoints' or 'don't use if you need to start a session.' The purpose is evident from context, but explicit guidance is missing.

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