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

With no annotations, the description carries full responsibility. It discloses important traits: free and no account needed, works for tokens issued to strangers, returns specific data (remaining budget, scopes, revocation status), and provides a signed answer for safekeeping. This goes well beyond a simple 'checks' claim.

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 sentences each serve a purpose: purpose, cost/access, and output/signature. The description is front-loaded with the main action and has no filler, making it efficient and easy to parse.

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?

Despite having no output schema, the description clearly lists the return values (remaining budget, scopes, revocation status) and notes the signed answer. This, combined with one simple parameter and clear usage context, makes the tool's behavior fully comprehensible without needing additional documentation.

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?

The schema already describes token_id as 'The delegation token to check', so coverage is 100%. The description adds useful context: the token may be issued by someone you've never met and relates to spending authority, enriching the meaning beyond the schema's minimal description.

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: checking whether an agent's spending authority is real, live, and large enough, before doing work. It uses a specific verb ('Checks') and identifies the resource ('spending authority'), and distinguishes itself from budget_status and other siblings by emphasizing verification of authenticity and the signed response.

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?

Explicitly states when to use: 'before you do work for it', and provides an alternative: 'Use this instead of trusting a claim'. This gives clear context on when the tool is appropriate and positions it as the verification step.

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