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

Annotations already declare read-only, idempotent, non-destructive, and closed-world behavior. The description adds useful context beyond that: weekly publication, return fields (value, IQR, population, week, month, vs-base changes, definition), and free public access. It does not describe rate limits or pagination, but the added context is substantial.

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 front-loaded with a clear headline, then uses grouped bullets to enumerate the nine KPIs, followed by return details and access tier. Every part serves a purpose, though the list is lengthy; it avoids filler and is well organized.

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?

With no output schema, the description compensates by describing the fields returned for each KPI. Annotations cover safety, and the schema covers parameters. It also notes the free tier versus PRO key, though it does not elaborate on the effect of the 'weeks' parameter beyond the schema.

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 three parameters, including enum-like values for 'group'. The description lists the three groups, which aligns with the schema but adds no new syntax or meaning beyond what is already provided.

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 states a specific resource: 'The nine market KPIs Attic Standard publishes each week,' and enumerates them by group. It is clearly distinguishable from generic stats tools by its focus on nine named KPIs, though it does not explicitly name or contrast with siblings like get_market_stats.

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?

No explicit when-to-use guidance or alternatives are provided. The description implies usage by listing the KPIs and noting the free tier ('fully public'), but an agent must infer that this tool is for retrieving published KPIs rather than, say, market statistics from a sibling tool.

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