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

Beyond read-only and idempotent annotations, the description discloses detailed behavior: carried-forward status fields and fill metadata, 14-day carry limits, gap-ledger conditions, derived spreads/medians, and windowClamped access-tier behavior. This is unusually rich behavioral context for an agent.

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 first sentence front-loads the core resource definition, and most subsequent detail is substantive domain behavior rather than filler. The single dense paragraph is longer than typical and could be better structured, but it is justified by the complexity of carried-forward and derived-series semantics.

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?

Although there is no output schema, the description explains the important response semantics: status values, sourceDate/fill behavior, derived medians/spreads, and windowClamped signaling. Given the complexity of the rate series and access tiers, an agent has enough information to call and interpret the tool 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%, so the baseline is 3, but the description adds meaningful semantics for slugs (LEVEL vs SPREAD and examples) and median:true, and it explains access-tier and window-size constraints that affect from/to and median requests. It stops short of adding syntax or format details beyond the schema, so it is strong but not maximal.

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 defines the resource as standardized rate series covering named LEVEL series, SPREAD series, per institution per day, with concrete slug examples. It does not explicitly distinguish this tool from siblings such as list_series, rate_history, or compare_rates, so the purpose is clear but not fully differentiated.

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?

It gives practical usage constraints, including median:true for market-median lines, access-tier date clamps, and Pro-tier window limits. However, it never states when to use this tool instead of siblings like list_series or rate_history, so alternative selection guidance is absent.

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