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

Beyond the readOnly/idempotent annotations, the description adds substantial behavioral detail: the exact return range (max 730, default 90), the empty-object condition when fewer than 3 snapshots, the 'Pro tier only' restriction, and the meaning of each output field (e.g., MACD histogram positive = bullish). This goes well beyond what annotations convey and is directly useful for interpreting results.

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 long but well-structured, front-loading the purpose and then listing fields in a bulleted list. The extra clauses like 'For informational purposes only' add minor noise, but the structure is clear and scannable, earning a 4 rather than lower because the detail is justified by the many output fields.

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 tool's complexity (many indicators, output schema exists), the description covers all essential aspects: what it returns, limits, tier requirement, and field semantics. It does not mention rate limits or advanced error cases, but these are uncommon in tool descriptions and the core information is complete. An agent can call this correctly with the given description.

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 100%, so both parameters are fully documented in the schema. The description largely repeats the `days` default/max and the `{}` condition, and does not add new meaning for the `symbol` parameter beyond what the schema already states. It meets the baseline but does not exceed it.

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 a specific verb and resource: 'Historical daily indicator snapshots for a stock' — explicitly distinguishing it from siblings like get_stock_history by focusing on technical indicators rather than raw price data. It also enumerates the exact indicator fields, making it clear what the tool returns.

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?

The description gives clear context that it is 'ideal for charting and trend detection', implying the use case, but it does not explicitly name alternatives or state when not to use it. It provides enough guidance for an agent to select it over siblings based on the indicator focus.

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