list_common_parameter_codes

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

With no annotations provided, the description carries the full burden. It discloses a key behavioral trait: 'No network call' and 'Returns a static table of {code, name, unit, description}' — describing the returned structure. This is good transparency for a zero-annotation tool, though it could mention whether the table is exhaustive or limited to common codes only.

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 compact, two sentences, and front-loaded with the primary purpose. Every sentence earns its place — purpose, examples, return structure, and the non-network caveat. Slightly redundant phrasing could be trimmed, but it is appropriately concise.

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?

For a static lookup tool with 0 params and no output schema, the description is quite complete: it covers what it returns, that it makes no network call, and the example use cases. It could list the full set of supported measurements or any limitations, but for its simplicity it is well-rounded.

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 tool has 0 parameters and 100% schema coverage (empty schema completes the picture). Baseline for 0-param tools is 4. The description adds useful context about what the returned record fields are ({code, name, unit, description}), which is additional value beyond the empty schema.

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 a specific verb+resource: 'Look up the 5-digit USGS parameter code for a common measurement.' It explicitly distinguishes from siblings by naming the purpose (getting codes before calling get_instantaneous_values) and noting this is a lookup/reference tool vs. the data-fetching siblings.

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 explicitly states when to use it: 'before calling get_instantaneous_values.' It gives the context (for common measurements like streamflow, gage height, water temperature, dissolved oxygen) and lists examples of what kind of lookup it serves, which orients the agent toward the correct choice among siblings.

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