get_i_bond_rate_historyFixed rate for new bonds, semiannual inflation rate and composite rate for every May and November announcement since September 1998, newest first, from the TreasuryDirect rate chart.
| Name | Required | Description | Default |
|---|---|---|---|
| limit | No | How many announcements, newest first. Default 20. |
Changes observed during successful MCP inspections.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The description goes far beyond the safety hints in the annotations by specifying the data source (TreasuryDirect), the specific announcement cadence (May and November), and the type of rates returned. This provides essential operational context for the tool's behavior.
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 definition is highly condensed into a single, powerful sentence. Every phrase serves a distinct purpose, from defining the data points to specifying the historical start date and source, achieving maximum information density.
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?
The tool is straightforward, and all necessary context—including data granularity, source reliability, and time window—is included. Given the lack of an output schema, the description is maximally complete.
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 schema coverage is 100%, but the description adds meaningful semantic context by explicitly stating the ordering convention ('newest first'), reinforcing the purpose of the 'limit' parameter. This helps solidify agent understanding of the result set structure.
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 resources being retrieved (Fixed rate, semiannual inflation rate, and composite rate) and the scope of the data (I bond rate history from TreasuryDirect). It clearly distinguishes this archival function from tools meant for current or calculated rates.
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?
While it does not explicitly state 'use this instead of X', the detailed description of historical data, announcements since 1998, and the specific content retrieved naturally guides an agent away from siblings focused on real-time or calculated values.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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