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

Annotations already declare destructiveHint=true and readOnlyHint=false, and the description adds real context on top: it is an authorization act that 'creates no Task and no wallet credit,' and it still requires signed token capabilities and live Space membership. That resolves the tension between a 'set' operation and a financial-sounding ceiling, though it never says whether an existing grant is overwritten or what happens on re-invocation.

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?

Three dense sentences plus the 'Person only.' fragment, with the identity requirement front-loaded and every clause carrying distinct information: action, constraint, side-effect scope, and prerequisites. Nothing is repeated from the schema or annotations.

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?

An output schema exists, so return values need no explanation, and the description covers prerequisites (token capabilities, Space membership) and side-effect boundaries. The gaps are the update semantics (overwrite vs. additive) and value constraints on the two numeric limits for what is an irreversible-sounding commitment.

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 only 33%: registration_id is documented in the schema, but the two credit-limit strings have no description and no format guidance. The description adds meaning (per-Task cap vs. UTC monthly commitment), yet leaves the string encoding, precision, and acceptable ranges entirely unspecified, so it only partially compensates.

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 definition gives a specific verb (authorize / set a grant) and resource (a linked agent's spending grant) with an explicit scope: per-Task maximum plus a UTC monthly commitment ceiling. It is clearly separable from agent_grant_list and agent_grant_revoke by its action, though it never names those siblings as adjacent operations, which keeps it short of a 5.

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?

'An agent can't fund itself' and 'Person only' establish the caller identity and the exclusion that matters most (no agent self-granting). What is missing is routing guidance toward agent_grant_list to inspect existing grants or agent_grant_revoke to undo one, so the agent must infer the lifecycle.

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