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

Annotations are only bare booleans (readOnlyHint=false, no destructive statement), so the description carries meaningful extra burden and pays part of it: it discloses that successful deliveries are saved privately to the account and consume shared research credits, and that provenance/gaps are preserved. It omits retry/idempotency behavior and permission requirements, keeping it short of a 5.

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 sentences, front-loaded with the verb+resource before constraints and cost. Some phrasing is abstract ('genuine gaps', 'remain distinguishable'), but nothing is redundant.

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?

An output schema exists, so return values need not be explained, and the description covers purpose, cost and side effects. For a 9-parameter, deeply nested tool with low schema coverage, however, it leaves operational details (how selectors, windows and price modes interact) to the schema and a referenced guide.

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 description coverage is low (33%), so the description should compensate more than it does. It gestures at key concepts ('explicit periods', 'observation times', 'Provider candles and derived samples remain distinguishable') that map to windows, time_axis and candle_basis, but it does not explain selector kinds, basis modes, or delivery params; the heavy lifting is done by the nested schema descriptions rather than the prose.

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 names a specific verb and resource ('Read a selected stored price series or candle format over explicit periods') and clarifies the scope ('stored', 'No upstream fetch'), which separates it from fetch/discovery tools. It does not, however, name any sibling tool such as read_evidence or discover_evidence to route the agent.

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 ('stored' series, 'No upstream fetch or market-event interpretation') but no explicit when-to-use/when-not or named alternative is given. The agent must infer that this is the read path for an already-selected price series from context alone.

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