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

With no annotations provided, the description carries the full burden of disclosing behavior. It covers freshness ('Snapshotted nightly'), caching ('1h cache'), data scope (rows of trading days, window aggregates), and constraints (days bounded to 365). This gives a solid behavioral picture for a read-only tool, though it omits potential edge cases like error handling or auth requirements.

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?

The description is information-dense but efficient, covering purpose, output details, aggregates, defaults, and usage in ~5 sentences. Every sentence adds value, and the structure flows logically from what it is to what it returns to how to use it.

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 complex tool with no output schema, the description thoroughly describes the return content (per-row fields, factor contributions, aggregates) and the query parameter. It could be slightly more explicit about the exact format of the aggregate object, but overall it is complete enough for an agent to select and invoke this tool correctly.

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 0%, so the description must fully explain the one parameter, and it does: 'Default 30 trading days; query ?days=N (bounded to 365)'. This adds meaning beyond the schema's bare 'days' string, specifying default, syntax, and upper bound, fully compensating for the schema's lack of description.

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 clearly states this is a daily PnL track record for the paper book, decomposed via the Carhart 4-factor model. It identifies a specific verb+resource+scope ('Daily PnL track record', 'Carhart 4-factor-decomposed', 'snapshotted nightly'), which distinguishes it from generic track-record tools, though it does not explicitly name a sibling alternative like tengu_copilot_track_record.

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?

Explicit guidance is given: 'Use this to ground any track-record claim the chat makes' with a concrete example. It also notes the default window and query parameter, providing clear context. However, it does not explicitly state when not to use this tool or mention alternatives, stopping short of a 5.

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