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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds useful operational detail beyond that: dedupe of defaults for unit/taxonomy and the limit cap (200 default, 2000 max), which helps the agent reason about result volume. Return shape is left to the output schema, so this is solid but not exhaustive.

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?

Two tight sentences, front-loaded with the core operation, followed by required inputs, defaults, and the alternative tool. No filler and nothing misplaced.

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 an output schema is present, the description need not explain return values, and annotations cover the safety profile. Everything an agent needs to select and invoke the tool — required inputs, format examples, defaults, cap, and the sibling alternative — is present.

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 the schema already documents all five parameters including defaults and the limit cap; the baseline is 3. The description restates the same defaults and adds period examples (CY2024, CY2024Q1, CY2024Q4I), but adds little meaning beyond the structured fields.

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 ('Compare reported XBRL values across companies') and scopes it to one concept and one reporting frame. It also names the sibling sec_financials as the different tool, so an agent can distinguish the two without opening a schema.

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?

Explicitly routes the agent: 'Use sec_financials for one company's statements,' which is exactly the when-not-to-use condition. Combined with the cross-company framing, there is no ambiguity about choosing between them.

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