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

Annotations already provide readOnly/openWorld/idempotent/non-destructive hints. The description adds behavioral specifics: exactly one GET, shared POST /api/a2a/check budget, no credentials or payment, and that third-party text is untrusted data. These enrich the annotations without contradicting them.

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?

Every sentence adds a distinct, useful fact: purpose, input format, outputs, version limitation, network impact, budget, alternatives, and security stance. It is front-loaded with the core purpose and contains no filler despite its density.

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 definition covers the tool's scope, input constraints, behavioral side effects, budget usage, relevant alternatives, limitations, and security posture. Since an output schema exists, the return-value gap is closed, and the description still supplements it by naming the categories of results. An agent has everything needed to select and invoke it correctly.

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 has 100% coverage for the single url parameter, including a full description. The tool description mostly reiterates that ('Give the full public HTTPS card URL') without adding new semantic constraints such as URL normalization, error handling, or format edge cases. Baseline 3 applies.

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 starts with 'Free A2A 0.3.0 card check', identifying a specific verb and resource. It further clarifies scope with 'Other versions remain unassessed' and enumerates concrete outputs (per-check states, bounded response evidence, suggested fixes and gaps), distinguishing it from generic checks.

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?

It explicitly states when to use this tool: for a free static check of A2A 0.3.0 cards. It also gives exclusions and alternatives: 'For authorized runtime tests and a signed repair kit, see /a2a-desk or buy_observation with item_id a2a_repair_kit' and notes it does not involve runtime tasks, credentials, or payment.

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