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

Annotations declare readOnlyHint, idempotentHint, and non-destructive, so safety is covered. The description adds important context beyond annotations: it outputs source-backed added/removed blocks (not semantic interpretation), and it explicitly enumerates missing paid features (prioritization, decision objects, checkpoint semantics, triage). However, it doesn't describe rate limits or auth needs, which is acceptable given the read-only hints.

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, front-loaded with the core action and return, followed by a clear negation of paid features. Slightly dense with the list of missing features, but no fluff and every sentence earns its place.

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 output schema exists, return values needn't be explained. The description covers the essential comparison behavior and distinguishes from a paid variant, but doesn't mention any prerequisites (e.g., both filings must exist, same issuer enforced) beyond 'same issuer'. With full schema coverage and output schema, this is nearly complete but leaves a small gap around error conditions or issuer matching behavior.

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 coverage is 100%, so the schema fully documents all parameters including item, limit, left, right, and identifier. The description adds no parameter-level meaning beyond what's in the schema, so baseline 3 is appropriate.

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?

States the specific verb (compare), resource (two filings from same issuer), and return type (source-backed added and removed disclosure blocks). It also clearly distinguishes itself from the paid operation by listing what it does NOT do, which helps an agent differentiate from siblings like check_disclosure_changes.

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?

Clearly establishes the context (comparing two filings from same issuer) and distinguishes from a paid alternative, but does not explicitly state when to choose this free primitive over siblings like check_disclosure_changes or build_disclosure_matrix. It provides clear boundaries but no positive selection guidance beyond 'lower-level free comparison primitive.'

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