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

With no annotations, the description carries the full burden and does so excellently. It discloses that the tool is retired, that there is nothing to buy, that it remains as a fallback, and what the replacement flow is. This is exactly the behavioral insight an agent needs.

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?

Three tightly-written sentences, with the critical RETIRED status front-loaded. Every sentence adds value: what changed, what to call instead, and why the tool still exists. No filler.

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?

For a retired redirect tool with one optional parameter and no output schema, the description is complete. It fully explains the state change, the replacement action, and the expected outcome, so an agent can handle this tool correctly without further information.

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 parameter, describing it as 'The site, e.g. example.com.' The description does not add meaning about the domain parameter itself; its mention of an email applies to the replacement tool, not to this one's parameters. A baseline 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 immediately marks the tool as RETIRED and explains its purpose: it exists only so older conversations get a helpful redirect. It explicitly names free_kit as the intended alternative, clearly distinguishing this tool from its sibling.

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?

It gives explicit when-to-use context ('older conversations'), and tells the agent exactly what to do instead: call free_kit with the owner's email. It also explains what will happen after that call, leaving no ambiguity about routing.

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