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

Annotations already declare readOnly, idempotent, non-destructive, open-world behavior. The description adds genuinely useful context beyond that: a concrete pricing model ($0.001 USDC per successful call via x402 on Solana) and an alternate HTTPS endpoint. This cost/payment transparency is valuable for an agent. It does not cover rate limits or error conditions, so not a 5.

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 core definition, then the example, edge case, pricing, and endpoint. Each element is useful, though the trailing pricing/endpoint sentence slightly dilutes focus from the operation itself.

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 correctly explains the return semantics (count of 0, orientation or none). Combined with annotation coverage of safety traits and a clarifying example, an agent has enough to call it correctly, though explicit param-to-role mapping would complete it.

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 0%, so the description must compensate. It conveys direction via the 'Two A4 pages fill an A3' example, implying the copy (inner) versus the target sheet (outer). It also documents output fields (count, orientation) that the schema lacks. But it never explicitly ties the inner/outer parameter names to their roles, leaving some ambiguity.

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?

The description states a specific operation: count how many copies of one sheet fit on another at full size, with rotation allowed. This is a clear verb+resource. However, it never names or distinguishes itself from close siblings like paper_scale, paper_size, or envelope_fit, leaving the agent to infer which tool handles which paper geometry question.

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?

Usage is implied through the A4-into-A3 example and the note that count is 0 when it does not fit, giving the agent a sense of the input/output relationship. But there is no explicit statement of when to choose this over paper_scale or paper_size, and no exclusions are given.

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