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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), so the description rightly spends its words on other traits: the data is precomputed and only current through the stated month, and the headline CAGR/drawdown/Sharpe figures are full-window over each entry's own start, making them non-comparable across entries. That non-obvious caveat is exactly the kind of behavioral context annotations cannot carry.

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 key action and the critical 'call this first' guidance are front-loaded, and every sentence carries information. It is dense and the long parenthetical enumerations of examples make it longer than strictly necessary, but nothing is filler.

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?

There is no output schema, yet the description enumerates the return payload (one-line description, holdings, headline metrics with start and data month, page and guide URLs). Combined with the filtering and staleness notes, an agent has everything needed to call and interpret it 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 100%, so the enum values and the query filter are already documented; baseline would be 3. The description adds meaning beyond the schema by tying each `kind` value to how the resulting ids are consumed as parameters elsewhere, and by giving concrete filter examples ('gold', 'TLT').

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 (list every portfolio and strategy accepted by id) and immediately enumerates the three kinds with counts and named examples. It distinguishes itself from siblings by explicitly mapping each kind to the parameter name used in analyze_portfolio, portfolio_returns, portfolio_risk, compare_portfolios and decompose_factors.

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?

Gives an explicit trigger: 'Call this first when you do not know an id, to avoid guessing.' It also names the alternative and the condition for it (use compare_portfolios for a like-for-like comparison), so the agent knows both when to use this and when not to.

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