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

Annotations already cover safety (readOnly, idempotent, non-destructive, closed-world), yet the description goes far beyond them: hard input limits (256 KiB / 1,000 lines), schema depth and node caps, enum cap, error cap of 50, refusal to echo values, rejection of unsupported keywords (refs/regex/format/combinators), and an explicit prompt-injection warning that returned evidence is untrusted data. This is exactly the extra operational context annotations cannot convey.

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?

Front-loaded with the core purpose and followed by limits and safety in a logical order; every clause carries information. The semicolon-chained density makes it slightly harder to scan than it could be, but nothing is padding.

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?

With no output schema, the description still explains exactly what comes back (validity plus error paths/rules capped at 50, no echoed values) and adds capacity limits and untrusted-data handling. An agent has everything needed to call it correctly and interpret the result.

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 load. It does well: 'text' is identified as JSON text with a 256 KiB bound, and 'schema' as a JSON Schema drawing on a documented subset with depth/nodes/enum limits. It is slightly incomplete in not clarifying whether the schema argument is passed as a string or an object.

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 ('Validate supplied JSON text against a bounded JSON Schema subset') and immediately enumerates the supported keyword set, which precisely bounds what validation means. No sibling tool does anything similar (log/HTTP trace analysis), so an agent can route correctly without opening the schema.

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 implied rather than stated: the tool clearly applies when you have a JSON document and a schema, and 'Offline' hints at when it is preferable to a network-dependent validator. However, there is no explicit when-to-use/when-not guidance and no alternatives named, so the agent must infer the selection conditions.

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