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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), and the description adds genuinely new context: the file is not stored, validation does not guarantee society acceptance, and there is a hard 256 KB ASCII input limit. That is real behavioral value beyond the annotations, though it says nothing about latency, rate limits, or partial-failure behavior.

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?

A single dense paragraph, front-loaded with purpose and return shape before moving to constraints and caveats. Nearly every sentence carries information (return fields, size limit, fallback URL, non-storage, acceptance caveat), though the enumeration of societies is slightly padded.

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 an output schema present, the description need not detail return values, yet it briefly does so helpfully. It covers format, size limit, storage, and the acceptance caveat; the only minor gap is no guidance on interaction with the sibling catalogue/report tools, which for a self-contained validator is acceptable.

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 description coverage is 100%, so the schema already documents cwr_text, filename (including the society-receiver-code rule) and recipient_profile. The description only restates the ASCII/256 KB constraint already encoded in maxLength, adding no semantics the schema lacks — baseline 3 is correct.

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 (CWR 2.1 file validation) and names the artifact domain (songs registered with MLC, PRS/ICE, SACEM, CMRRA), which no sibling tool covers. An agent can immediately tell this apart from check_catalogue or lookup_recording.

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 implies when the tool applies (checking a CWR 2.1 file before society submission) and routes oversized files (>256 KB) to a web upload URL, which is useful. However, it never states when to prefer this over sibling tools like check_catalogue, nor any prerequisites beyond format/size, so usage is only implied rather than explicit.

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