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

With no annotations, the description carries the full burden. It discloses the cost ($0.01 only on change, free on no-change), the cursor behavior (each call returns a fresh cursor), and that it is a delta/diff operation. It doesn't explicitly state read-only, but that's strongly implied by the polling nature. It could mention the baseline behavior when omitting 'since,' but that's in the schema.

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 sentences with zero waste. The critical cost note is front-loaded, then the diff mechanics. Every word serves a purpose.

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?

It covers the key aspects: cost model, cursor usage, and the diff categories (added, worsened, resolved). It lacks an explicit description of the baseline output when 'since' is omitted, but that's in the schema. The tool is simple enough that this description is nearly complete.

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 coverage is 100%, so the baseline is 3. The description adds usage context for 'since' (pass it to get changes) and clarifies the cursor is reused, but the payment param's workflow is already fully documented in the schema. No significant extra meaning is added beyond the schema.

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 specifies a clear verb and resource: 'Changed-only distress diff' — it returns only what moved since a cursor. It also distinguishes itself from the whole-index alternatives by saying 'instead of re-buying the whole index,' which sets it apart from sibling tools like farm_distress or farm_summary.

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 explains when to use it: for cheap polling, passing a cursor to get deltas. It mentions the payment condition (only charged on change) and contrasts with 're-buying the whole index,' implying when not to use it. It doesn't explicitly name alternative tools, but the context is clear enough.

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