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

Annotations already cover read-only, idempotent and open-world. The description adds genuinely new context beyond them: the data is pre-stored, no model is executed on call, the caller needs api:read, and the response includes an app_url pointing at the Daily Moves screen.

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?

Four short, front-loaded sentences with no filler; the permission note is tucked into a parenthetical at the end where it belongs. Slightly dense use of parentheticals, but nothing wasteful.

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 one-parameter read with rich annotations and no output schema, the description covers what is returned, that it is stored rather than computed, and the auth requirement. It omits what happens when no captured context exists for a mover, which would be the last missing piece.

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% — the pattern is present but undocumented. The description compensates by naming the parameter's meaning (US-equity ticker) and giving a concrete example (CXMT), which is more than the schema provides, though it does not explain the pattern's bounds or edge cases.

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 and resource: it retrieves the stored research context (news, catalysts, evidence) behind a symbol's big move. The symbol-scoped phrasing and the ticker example distinguish it from the list-style sibling get_daily_moves and from the plan-oriented get_daily_move_plan, though no sibling is named explicitly.

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?

Usage is implied by the question it answers ('Why a Daily Move moved'), and 'Stored only — it never runs a model' implicitly steers agents away from asking for fresh analysis. But there is no explicit when-to-use/when-not guidance and no named alternative for live or unrestricted research.

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