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

The readOnlyHint annotation already covers the safety profile. The description adds some behavioral context by specifying hourly resolution and session scope, but it does not disclose how far back 'previous sessions' reaches or what the returned candle structure is.

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 a single front-loaded sentence with no filler. It is efficient, though quite terse; useful context about response format or usage is omitted.

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?

Given the simple read-only nature and good schema documentation for two of three parameters, this is minimally viable. However, with no output schema, an agent is left without information about the candle payload, session/timezone semantics, or behavior beyond the bare scope phrase.

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?

The schema already documents period and intervalSec well, including enums and defaults. The description adds minimal parameter meaning beyond implying hourly bars, and the required symbol parameter has no semantic explanation. This is adequate middle ground given 67% schema coverage.

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 states the resource ('hourly candles') and its scope ('current and previous sessions'), which aligns with the tool name. It is clear enough for selection, but it does not explicitly differentiate it from siblings like get_price_series or get_intraday_quote.

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?

There is no guidance on when to use this tool versus alternatives. The description only gives a scope hint; it never mentions exclusions, prerequisites, or sibling tool comparisons.

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