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

Since no annotations are provided, the description carries the full burden. It discloses the return value (shareable URL) and the follow-up actions, but does not discuss potential side effects (e.g., whether the session is temporary) or permission requirements. Overall adequate.

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 concise, front-loaded with 'IMPORTANT,' and conveys the critical workflow in just a few sentences. Every sentence serves a purpose with 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?

Given the tool's complexity (9 parameters, no required ones, no output schema), the description covers the essential workflow and return value. It could briefly mention what the session object is, but the overall guidance is sufficient for correct invocation.

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 67% (6 of 9 parameters documented). The description does not add additional meaning beyond what the schema already provides. Baseline at this coverage is 3, and the description does not compensate by explaining parameter relationships.

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: 'Create this FIRST when helping someone find a rental.' It explains what it returns (a shareable URL) and how it fits into the workflow, distinguishing it from siblings like rental_session_add.

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 provides explicit usage guidance: create first, then add properties, then share the URL. While it clearly indicates when to use this tool, it does not explicitly state when not to use it or provide alternatives beyond the sibling context.

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