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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds real value beyond them: it discloses the authentication model ("No key; the token is enough") and, with no output schema present, describes the returned fields (state, amount_usd, purpose, pay_by, payment methods while open).

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?

One front-loaded sentence that leads with the verb and lookup key before enumerating outputs. The parenthetical field list is dense but every element is informative; no filler.

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 single-parameter read with annotations and no output schema, the description covers the key, the auth model, the state enum values, and the return fields. Only the token format constraint and error/expiry behavior are 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 0%, so the description must carry the single parameter. It explains that the token alone suffices and is a bearer credential, which is meaningful beyond the schema, but it never mentions the required `pt_` + 22-character format that the schema pattern enforces.

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 ("Read a pay link by its token") and enumerates the fields returned, so the agent knows exactly what the tool yields. It does not name its near siblings (bounty_pay_link, balance_topup_link, bounty_get) to disambiguate read-versus-create, though the verb "Read" and the token lookup imply the distinction.

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 only implied: you call it when you hold a pay_token and want its state. There is no explicit when-to-use versus bounty_pay_link or balance_topup_link, nor a statement of what to do if the link is expired or the token is invalid.

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