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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false. The description adds genuinely new behavioral context beyond those: the account-tier gating (no account = date/time for one ticker or next 3 reporters; free = up to 10 with estimates; Pro = full calendar plus options-flow intent label).

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?

Three dense sentences, front-loaded with the resource and returned fields, then usage, then tier limits. No filler, though the tier sentence is packed tightly and could be slightly clearer.

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 read-only calendar tool with no output schema, the description covers returned fields, usage variants, window/default semantics, and access-tier limits. It leaves only the earnings_current-vs-earnings_calendar distinction and return format specifics unaddressed.

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 all three parameters (days, limit, ticker) are already documented in the schema. The description restates the days window and default (7) and the ticker-as-optional idea, adding only marginal meaning beyond the schema, so the baseline 3 applies.

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+resource: 'Upcoming earnings reports' with the returned fields (date, before/after market, EPS and revenue estimates). The word 'Upcoming' implies a time direction, but the description never explicitly distinguishes it from the sibling earnings_current (likely historical), so differentiation is left to inference.

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?

Gives concrete when-to-use guidance via two example intents: 'Pass a ticker for when does NVDA report?' vs 'omit it for who reports this week?', and notes that days sets the window. It stops short of naming an alternative sibling tool or when-not-to-use conditions, so it is clear but not exhaustive.

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