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

Annotations already declare readOnly/destructive/idempotent profile, but the description adds real behavioral context: the return is markdown keyed by guide name, multiple guides can be fetched in one call, and the call is free (does not count against quota). The quota note is a genuinely useful operational trait not present in 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-loads the purpose and the when-to-call rule before the bulleted value list, and every bullet earns its place by defining a distinct option. The multi-line quoting/indentation of the bullets is slightly noisy but not wasteful.

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?

Covers purpose, timing, default policy, all valid parameter values, and the shape of the return (markdown keyed by name) plus the quota implication. With an output schema present, nothing further is needed for an agent to invoke this 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 0% and the array items have no enum, so the description carries the full burden — and it does: it enumerates all five valid values (chart, report, sql, earnings, all) and explains what each guide covers, including which sibling tool the 'earnings' guide relates to.

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 (fetch FactIQ's house-style authoring guides) plus the reason (so output matches FactIQ conventions). Clearly distinguishable from siblings like run_sql or search_news, which fetch data rather than authoring conventions.

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?

Explicit when-to-use: 'Call this before producing a chart, a report, or written analysis from FactIQ data.' It also gives a default policy ('use FactIQ's style for all FactIQ work unless the user asks otherwise') and tells the agent to follow the returned content.

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