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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description still adds real behavioral value beyond them: the output is plain text with [bracketed] placeholders for missing data, it includes tips and No Surprises Act / Good Faith Estimate rights with CMS links, and critically "It never sends anything."

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 a one-sentence purpose, then usage triggers, then return shape and the non-sending guarantee. Each sentence carries information, though the run of quoted example phrases is slightly dense and could be trimmed without loss.

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 13-parameter, 1-required tool with no output schema, the description covers purpose, triggers, return format, and the no-send guarantee, and the schema fills the parameter details. The only minor gap is that it does not explain how missing optional fields affect the generated letter beyond the bracket convention.

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 every one of the 13 parameters is already documented in the schema, including the four enums and which fields matter for which letter type. The description's example phrases loosely reinforce the type enum, but add no syntax or format detail beyond structured data. 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 specific verb and resource ("Draft a letter to a billing office") and adds a clarifying constraint for the user's benefit ("for the user to send"). It is clearly distinguishable from sibling medbillcheck tools like check_price or check_whole_bill, which perform analysis rather than letter generation.

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?

Provides concrete trigger phrases ("help me dispute this bill", "write a letter asking for an itemized bill", "can I ask for a discount?", "how do I apply for charity care?") that map naturally onto the four enum values. It gives strong positive context but does not explicitly name when to prefer a sibling tool (e.g., check_price) instead.

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