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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds beyond that the 'approved' restriction on eligible companies and the 2-4 cardinality, which is genuinely useful selection context.

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?

Front-loaded with purpose, then usage. The attribute enumeration is long but earns its place by defining the comparison output, and there is 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?

No output schema exists, so the description usefully enumerates the rows returned (entity type, category, location, founded, etc.), making the return shape reasonably predictable. Minor gap: no note on error handling for fewer than 2 or more than 4 entries.

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% and the single 'listings' parameter already documents accepted identifier formats (slug, name, FL-ID, URL). The description only restates the 2-4 bound, so it adds little beyond the schema; baseline 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?

States a precise verb and resource ('Compare 2 to 4 approved FirmLedger companies side by side') and enumerates the compared attributes, so an agent can tell it apart from search_listings or get_listing without opening a schema.

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?

Explicitly names the predecessor and trigger: 'Use after search_listings when the user wants to weigh companies against each other.' It gives a clear when-to-use and an alternative, though it does not state when not to use it or the behavior if listings are unapproved.

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