format_format_number

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

With no annotations, the description carries the full burden. It correctly indicates the core behavior (formatting with thousands separators) but does not disclose that parameters allow custom separators and decimal places, which could affect formatting. However, for a simple formatting tool, the basic behavior is transparent.

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 very concise (one sentence with example) and gains high efficiency. It is front-loaded with the purpose. Though it could benefit from slight expansion on parameters, it wastes no words for the basic use case.

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?

Given the simple tool and existence of an output schema, the description is moderately complete. It covers the default operation but lacks explanation of optional parameters and edge cases (e.g., what happens if no separators provided). The agent can infer basic usage but may miss customization options.

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 has 4 parameters (value, decimals, thousands_sep, decimal_sep) with 0% description coverage. The description only illustrates the default behavior (commas and period). It does not explain the optional parameters or their effects, failing to add meaning beyond the parameter names.

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 explicitly states 'Format with thousands separators' and provides a concrete example (1234567.89 → '1,234,567.89'), making the tool's purpose immediately clear. It also distinguishes itself from sibling formatting tools like format_format_currency or format_format_percent.

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 guidance is given on when to use this tool versus alternatives. For instance, it doesn't mention that format_format_currency would be more appropriate for monetary values or that format_format_percent handles percentages. The agent must infer usage from the name alone.

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