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

Beyond the readOnlyHint and openWorldHint annotations, the description adds substantial behavioral detail: it uses the Federal Register open-comment window, is fully functional without an API key, and enriches results with embedded Regulations.gov comment counts only when the key is configured, without an extra rate-limited call. This is genuinely useful context about dependencies, auth, and performance.

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, front-loaded with the core behavior, and then adds essential operational and follow-up context in a few short sentences. Every sentence serves a purpose: behavior, user question, key behavior, and related tools.

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?

Together with a fully documented input schema, an output schema, and annotations, the description supplies enough context: data source, sorting, filtering, key-dependent enrichment, no-added-rate-limit behavior, and clear next steps. There are no meaningful gaps an agent would have to guess.

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 input schema already documents all parameters at 100% coverage, so the description does not need to compensate. The phrase 'filterable by agency slug and topic' adds a high-level mapping to parameters and the sorting by closing date is helpful context, but the schema already carries most of the parameter meaning.

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: 'List rules currently open for public comment,' with clear filtering and sorting behavior. It immediately distinguishes the tool from siblings by centering on the open-comment window and posing the natural use-case question, 'What can I still weigh in on?'

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 for when to use the tool: when the user asks about rules open for comment and actionable deadlines. It also points to the right follow-up tools, regulations_get_document and regulations_find_comments. It does not explicitly contrast it with regulations_search_rules or other sibling search tools, so explicit when-not-to-use guidance is missing.

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