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

Annotations already declare readOnlyHint=true and idempotentHint=true, covering the safety profile. The description adds meaningful behavioral context: it returns data for the current fiscal year only, lists the specific data elements, and frames the tool as the initial navigation step. This goes beyond merely restating the read-only nature, though it does not mention pagination or limits—minor given the output schema likely describes the response.

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?

Two sentences with no wasted words. The first sentence front-loads the core purpose and output content; the second provides critical usage context by naming downstream tools. Every sentence earns its keep.

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 simple list tool with optional sort parameters and an output schema, the description is complete. It tells the agent exactly what will be returned, scopes the data to the current fiscal year, and explains how it fits into the broader toolchain. Required parameters are none, so no input gaps exist. The output schema covers return structure, so the description doesn't need to.

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?

Schema description coverage is 100%: both 'sort' and 'order' parameters have clear enum values, defaults, and descriptions in the schema. The tool description does not add any extra parameter semantics beyond what the schema already provides, so the baseline of 3 applies.

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 states a specific verb ('List'), a precise resource ('all top-tier federal agencies'), and the exact fields returned (toptier codes, agency slugs, budget authority, obligation totals). It also explicitly distinguishes itself from usaspending_get_agency by positioning itself as the entry point for agency navigation, so an agent can clearly tell them apart.

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 explicitly says to use this tool as the entry point for agency navigation and notes that the toptier codes and agency slugs it returns are required inputs for usaspending_get_agency and agency-based filters. This gives clear when-to-use guidance and implies when not to use it (i.e., when you already have an agency identifier and need details).

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