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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds useful behavioral context: the score is a deviation-based momentum measure, monthly since 1964, and returns specific fields. The update cadence is also noted. This goes beyond the annotations without contradicting them.

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 three sentences: output definition, usage triggers, and update frequency. Every sentence carries distinct value and the opening sentence immediately states the purpose and return fields, making it appropriately sized and front-loaded.

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?

Despite lacking an output schema, the description enumerates the return fields, explains the data source and calculation, and gives usage context and update frequency. The optional days parameter is handled entirely by the schema. This is a complete description for a simple read-only indicator tool.

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?

The input schema has full coverage (100%) for the single optional `days` parameter, including its purpose and tier-based behavior. The description adds no parameter-level details, but the schema already does the heavy lifting, so the baseline of 3 is appropriate.

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 clearly states the tool returns a 0-100 building-permits momentum score, specifies the data source (FRED PERMIT) and calculation (recent vs trailing-mean % deviation), and names the output fields (momentum_score, recent_value, deviation_pct). The verb 'Returns' plus the specific resource and output details distinguish this from generic sibling tools.

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?

The description provides explicit when-to-use guidance with a list of user intents (building permits, housing starts, homebuilding activity, residential construction momentum, leading housing-supply indicators) and decision contexts (REIT allocation, homebuilder exposure, land-acquisition). It does not, however, mention when not to use it or suggest an alternative tool, so it stops short of a perfect 5.

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