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

Annotations cover the safety profile (readOnly, idempotent, non-destructive), and the description adds genuinely non-obvious behavior: dates are projected from filing cadence, are 'held' rather than rolled, and are flagged overdue when a projection lapses. That derivation rule is exactly the kind of trait an agent cannot get from structured fields.

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?

Front-loaded with the core purpose, then usage triggers, then exclusions and args in a compact sequence. It is dense as a single paragraph but nearly every clause carries information; a light structural break before the 'Not for' clause would improve scanning.

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 lookup with an output schema and fully documented parameters, the description covers purpose, triggers, exclusions, projection semantics, and ordering. An agent has everything needed to select and call it correctly.

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 coverage is 100% and the schema already explains entity formats (ticker/name/CIK), the types enum values, and limit ordering, so the baseline is 3. The description's 'Args: entity; types; limit' restates the names but also reinforces the ordering contract ('nearest first'), which adds slight value beyond the schema.

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 and resource: 'the next earnings date projected from its own filing cadence ... then trial readouts, nearest first.' It also defines the projection semantics (held, not rolled, marked overdue), so an agent knows exactly what the timeline contains versus a raw filing list.

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 explicit trigger phrasings ('when does X report next', 'what's coming up for X') and explicit exclusions routed to named siblings: past events to get_filings, actual results to answer. Nothing is left to inference.

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