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

With no annotations, the description carries the full burden. It discloses that the tool issues a signed grant that the agent adopts, and that transactions are autonomous within defined limits. However, it does not mention side effects, irreversibility, or required permissions beyond the schema fields.

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?

The core description is a single dense sentence that conveys most needed info, but it is padded with a tagline and pricing info ('$0.00 USDC, tier: free') that do not aid tool selection. This is unnecessary fluff, though not overly verbose.

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?

The tool has 10 parameters, no output schema, and no annotations. The description explains the purpose and main constraints but does not clearly state the return value (the signed grant is implied but not explicit) or any prerequisites/preconditions. The schema covers parameter semantics, but behavioral and output details 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 100%, so baseline is 3. The description adds meaning by grouping parameters into functional categories: 'per-action and rolling-window USDC caps' clarifies spend_max_usdc vs daily_cap_usdc, and 'velocity limit and expiry' highlights velocity_max and expires_at. This goes beyond the individual schema descriptions.

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 clearly states the tool's function: 'Author a signed spend mandate for an agent' with specific controls (caps, allowlists, velocity, expiry). It distinguishes this from generic permission tools by referencing 'PERM_v0 grant' and 'agent adopts', but does not explicitly contrast with siblings like onyx_perm_grant.

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?

The description implies usage: when you need to set up autonomous agent spending with boundaries. It gives a clear context ('Transacts autonomously, within the boundaries you define') but does not mention when not to use it or explicitly name alternative tools.

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