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

Annotations already declare read-only/non-destructive, but the description adds genuinely new behavior: results are a sampled comparison rather than a complete redline, examples are bounded to eight sections, and the tool reports when no prior filing exists. The 'preceding available' wording also explains why idempotentHint is false.

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?

Three tight sentences, front-loaded with the operation and its scope, then the output shape, then the key limitation. No filler.

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?

An output schema exists, so return values need not be detailed, yet the description still outlines counts and bounded examples. It also covers the no-prior-filing edge case and the sampling caveat; only the filing_id semantics remain unaddressed.

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 0% for the single filing_id parameter and the description says nothing about it. The regex pattern in the schema makes the ID format self-evident, so this is a survivable gap, but the description contributes no meaning beyond the 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 names a specific verb (compare), resource (SEC filing), and precise comparison baseline (preceding available reporting period of the same company and form). This cleanly separates it from read_filing_section and filing_facts, which retrieve rather than diff.

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 defines the exact comparison context (same company, same form, preceding available period), which tells the agent when this tool is the right choice. It does not name a sibling alternative or state exclusions, but the scope is unambiguous.

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