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

Annotations already cover read-only, idempotent, non-destructive, open-world, but the description adds genuinely new behavior: facts sourced from each product's own site, unstated fields marked "not stated" rather than guessed, out-of-catalog apps excluded and named, and per-app links that resolve to the vendor's site. That is meaningful disclosure beyond the structured 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?

Front-loaded with the comparison scope and dimensions, then usage, then grounding caveats and link-presentation guidance. Three short paragraphs, each doing work, though the closing link instruction is slightly verbose for what it conveys.

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?

With no output schema, the description carries the return-shape burden and does: results contain per-app links on names, unstated fields appear as "not stated", and excluded apps are named. An agent has everything needed to call and present results correctly.

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%, so both parameters (names, focus) are already documented, including the 2-5 bounds and focus examples. The description restates the 2-5 constraint and echoes the same focus examples, adding no new semantics over 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?

Specific verb (compare) plus resource (apps), with explicit scope (2-5, side by side) and the exact dimensions compared (pricing, free tier/trial/OSS/self-hosting, shared vs unique features). It is clearly distinguishable from get_app and search_apps, which fetch or find rather than compare.

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?

Gives a clear triggering condition ("when the user weighs specific apps against each other") with concrete examples ("Notion vs Coda", "which of these is cheapest") and notes that out-of-catalog apps are excluded and named. It stops short of explicitly routing the agent to search_apps to discover or validate app names before calling.

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