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

Annotations already declare readOnlyHint=true, and the description adds meaningful behavioral context: it covers both upcoming and historical data and supports filtering. The mention of the Finnhub REST endpoint also provides a transparency signal about the underlying API. However, it does not disclose edge cases like default date ranges or response shape, but given the read-only annotation, this is acceptable.

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 two sentences, front-loaded with the core purpose, and includes the REST endpoint as a useful reference. No unnecessary words or fluff.

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 simple read-only calendar tool with all parameters documented and no output schema, the description is sufficiently complete. It states the resource type, time range coverage, and filter options. It could be more detailed about return values, but the absence of an output schema and the tool's simplicity make this acceptable.

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?

All three parameters (to, from, symbol) have descriptions in the schema, covering 100% of parameters. The description's mention of 'date range and/or symbol' simply summarizes the schema without adding additional meaning. Since schema coverage is high, a baseline of 3 is appropriate.

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 clearly identifies the tool as a calendar of upcoming and historical earnings releases, with optional filtering by date range and/or symbol. This distinguishes it from sibling tools like finnhub_earnings_surprises and finnhub_ipo_calendar, making the purpose unmistakable.

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 implies when to use this tool: when you need earnings release dates, optionally filtered by date range or symbol. It provides context but does not explicitly name alternatives or exclusions. The context is clear enough for an agent to select this over peers.

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