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

Annotations cover the safety profile (readOnly, openWorld), yet the description still adds real operational context: the concrete endpoint, 0.005 credits per call, and that it works credential-free up to 25 calls/day. That cost/rate-limit/auth disclosure is exactly the beyond-annotation value the rubric rewards.

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?

Front-loaded and tightly packed: scope sentence first, operational metadata in a parenthetical. Dense but every clause earns its place; nothing is padded.

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 read-only list tool with no output schema, the description covers what rows qualify, the window semantics, cost, and auth limits. The only lightly covered area is return shape/pagination, which is minor given the annotations and lack of output schema.

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?

With 50% schema coverage, the description compensates by expanding the materiality logic, mapping the OR conditions (new positions, full exits, ≥25% share-count shifts, ≥$100M size) onto the status/min_position_usd filters. The schema already documents 'since' vs 'filed_since' well, so this is additive rather than redundant.

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?

States a specific verb+resource ('13F position changes') and pins down the exact scope: entire 60-guru roster, requested window, materiality threshold. The 'changes' framing cleanly separates it from the sibling smart_money_holdings without needing to name it.

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 materiality definition (new/exits/≥25%/≥$100M OR) implicitly tells the agent what this tool surfaces, but there is no explicit when-to-use vs smart_money_holdings or guru_moves, and no stated exclusions. Usage is inferable but not guided.

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