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

Annotations already establish readOnlyHint=true, and the description goes beyond that by disclosing the return payload: the official source, the date it was checked, and a compressor page pre-set to a safe target size. It adds real value about what the agent gets back, though it says nothing about auth needs, rate limits, or behavior for unrecognized portals.

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, cleanly split between what the tool returns and when to invoke it, with the core purpose front-loaded. The example list is compact and every clause 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?

For a one-parameter, read-only lookup with no output schema, the description covers what is needed: the returned fields (limit, format, source, check date, compressor link) and the invocation trigger. Annotations already carry the safety profile, so nothing essential is missing.

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% and the single 'portal' parameter is already documented in the schema. The description's example list largely duplicates the schema's own examples, adding only marginal meaning. Baseline 3 is appropriate when the schema does the heavy lifting.

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 specific verb and resource: 'Look up the official file size limit and accepted format for an upload portal or service', with concrete examples (IRCC, USCIS, ImmiAccount, CM/ECF, Gmail, Turnitin, Etsy). The scope is unmistakable and clearly distinct from tool-finding siblings, but it never names or contrasts with an alternative, so it stops short of explicit sibling differentiation.

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 an explicit trigger: 'Use this when a user says a portal rejected their file or asks how big a PDF may be.' That covers the main invocation context well, but it offers no exclusions or named alternatives (e.g., when to prefer find_pdf_tool or get_pdf_tool instead).

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