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 determinism ('Deterministic, fixture-verified'), per-item error handling ('one bad date never fails the batch'), rate limits and budget usage ('free for guests... pass your Guild api_key'), and the return of a signed provenance envelope. This is rich behavioral context beyond any structured annotation.

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 longer due to embedded JSON schemas, but each section is purposeful. It is front-loaded with the primary purpose, followed by behavior, authentication, and schemas. The structure is logical and not bloated, though the inline schemas add necessary length.

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 tool's complexity and the absence of annotations, the description is exceptionally complete. It covers input, output, error semantics, auth/budget, determinism, and provenance, while the output schema already documents the return shape. No critical context is missing.

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 actual input schema only defines `payload` as a generic object and `api_key` without detail. The description compensates by embedding the exact payload JSON Schema, specifying `dates` (array of strings, 1-500 items) and `dayfirst` (boolean), and explaining the role of `api_key`. This fully clarifies parameter semantics.

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 begins with a specific verb and resource: 'Normalize arbitrary date strings to ISO 8601.' It provides concrete examples of input formats and clearly distinguishes the tool from siblings like ag_text_regex_extract, which handles regex extraction rather than date normalization.

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 gives clear context on when to use the tool: when messy date strings need parsing. However, it does not explicitly mention alternatives, when not to use it, or exclusion criteria. Thus, the usage guidance is implied rather than explicit.

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