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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description still adds meaningful behavior beyond that: it is free, capped at 4 MiB, validates the C2PA manifest specifically against Proofestry's own records, and warns that absence of marks is not proof of an unmarked file. That interpretation caveat is the single most important behavioral fact about this tool and is not derivable from any structured field.

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 definition is dense and front-loaded: what is checked comes first, followed by the critical negative-result caveat and the size limit. The trailing "MCP tool: `verify_provenance`" is pure redundancy with the tool name and earns nothing, which keeps this from a 5.

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?

For a one-parameter, read-only check with no output schema, the description covers what is inspected, the size ceiling, the cost, and how to interpret a null result. The only gap is that "Reports what was found" stays abstract about the shape of that report, which matters somewhat given there is no output schema.

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?

There is a single parameter with 100% schema description coverage, so the schema already fully documents file_base64 including the 4 MiB limit; the description's "Up to 4 MiB" merely restates it. No additional encoding or size-handling nuance is added. Baseline 3 applies when the schema does the heavy lifting.

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 gives a specific verb and resource ("Checks a file for Proofestry's marks") and enumerates exactly what is inspected: the C2PA manifest validated against Proofestry's records, the invisible watermark, and an exact fingerprint of delivered files. That is far more specific than a generic 'verify' tool. It does not name a sibling such as detect_provenance or scan_file, so the agent gets no explicit disambiguation.

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 agent can infer this is the tool for asking 'is this file Proofestry-marked?' and the "Free" note plus "Up to 4 MiB" gives practical context. However, there is no explicit when-to-use vs. when-not, and no pointer to the many sibling verification or scanning tools, leaving the agent to infer routing from names alone.

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