Check the Leboncoin session

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

Adds rich behavioral context beyond annotations: the tool doesn't throw, defines what each state means, and warns that datadome_blocked is not fixed by reauthentication. It also tells the agent never to ask for a password. This complements the annotations (readOnly, openWorld) without 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 dense yet well-structured, with a clear state list and follow-up actions. Every sentence adds value, including the nuanced datadome_blocked distinction and the manual login command. No 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?

Despite having no output schema, the description fully specifies all possible return states and the correct user-facing action for each. It also includes the manual login flow and a security note, making it self-contained for an agent.

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 schema already provides 100% coverage for the single 'country' parameter. The description does not add parameter-specific details, but no gap exists, so a baseline of 3 is appropriate.

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 'Reports whether a usable Leboncoin session exists' and enumerates specific states, making it distinct from siblings like whoami or diagnose. The verb 'Reports' and the resource 'session' are precise.

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 gives actionable guidance: only prompt sign-in when reauthenticationRequired is true, and provides the exact manual login command. However, it doesn't explicitly compare with alternative tools or state when to choose this over them, so it's clear but lacks exclusionary guidance.

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