diff_report

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

No annotations are provided, so the description carries the full burden. It usefully discloses the report's contents (old → new price moves, delistings, membership changes), which is meaningful behavioral context, but it omits access requirements, cost/latency, size limits, and pagination behavior for what is potentially a large multi-project report.

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?

A single front-loaded sentence that puts the verb ('What changed') first and then lists the four change categories. No filler, no repetition of the tool name, and the column-style enumeration keeps the return content scannable.

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?

With no output schema, the description correctly takes on the job of explaining return content and does so by enumerating the four change types. It is nearly complete for a read-only diff tool; the only real gap is that 'observed projects' (tracked vs. all indexed) is never defined.

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?

Only one parameter and schema description coverage is 100%, so the baseline is 3. The phrase 'since a timestamp' and 'old → new' echo the schema's ISO date/datetime semantics but add no format, timezone, or boundary-inclusivity detail beyond what the schema already states.

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 gives a specific verb ('what changed'), a clear resource scope ('all observed projects since a timestamp'), and enumerates the exact change categories (price moves, new projects, delistings, membership changes). That scope distinguishes it from siblings like price_history (single-project history) or secondary_trends without opening their schemas.

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?

There is no 'when to use this' guidance, no exclusions, and no named alternative. An agent can infer it is a reporting/diff tool from the verb, but nothing tells it whether to prefer this over price_history, refresh, or list_tracked when investigating changes.

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