free_model_changes

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

No annotations exist, so the description carries the burden alone. It usefully discloses that the diff is against a *last local scan* — a stateful dependency that an agent must know about — but never says what happens when no prior scan exists or whether the comparison is cached/stale.

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?

Two short sentences, zero waste, with the core operation stated first and the rationale second. Nothing is padded or repeated.

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 zero-parameter read tool with no output schema, the description covers what it does and the shape of the result (appeared/disappeared). The main missing piece is the failure mode when a local scan baseline is absent.

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 takes zero parameters, and the description correctly implies a parameterless call. Baseline 4 applies since there is nothing for the schema to document.

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?

Uses a specific verb ("diff") against a specific resource (live free catalog vs. last local scan) and states the output shape: models that appeared or disappeared. It is clearly distinguishable from list_free_models and free_providers by implication, though neither sibling is named.

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?

"Check before hard-coding a model id" gives one concrete trigger, and "free lineups rotate" explains why. However, there is no explicit routing versus list_free_models (full list) or free_providers, and no when-not-use guidance.

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