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

Annotations already establish the safety profile (readOnlyHint=true, idempotentHint=true, destructiveHint=false), so the bar is lower. The description adds real value beyond them by disclosing what comes back: the official source, the date it was checked, and a compressor page pre-set to a safe target size — important since no output schema exists.

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 verb and resource, then the trigger condition. Two sentences, no filler. The parenthetical example list is longer than strictly necessary but does useful disambiguation work rather than being decoration.

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-value burden and does so (source, checked date, compressor page). One parameter fully documented. Minor gap: no mention of behavior when a portal is unknown or has no official limit on record.

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 baseline is 3. The description earns slightly above baseline by broadening the example set well past the schema's 'IRCC'/'USCIS' to ImmiAccount, CM/ECF, Gmail, Turnitin and Etsy, signaling that non-government consumer services are valid values.

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+resource: 'Look up the official file size limit and accepted format for an upload portal or service.' It clearly distinguishes itself from the pdf-tool siblings by scope (limits/formats rather than tool discovery), though it never names or explicitly contrasts a sibling such as find_official_form, which the example list ('IRCC, USCIS') could otherwise be confused with.

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?

Explicit trigger given: 'Use this when a user says a portal rejected their file or asks how big a PDF may be.' That is a clear when-to-use condition, but there is no when-not-to-use guidance or named alternative for adjacent cases (e.g. form-finding or actual compression workflows).

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