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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description adds the base64 encoding requirement, but that is already in the schema, and it says nothing about multi-sheet XLSX handling, size limits, or malformed-file behavior. With annotations carrying the safety burden, a 3 is appropriate.

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 sentence with zero waste; the verb, accepted formats, and output format are all front-loaded. Nothing could be trimmed without losing information.

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?

An output schema exists, so return values need not be explained, and the annotations cover the safety profile. What remains thin is edge-case behavior (multi-sheet workbooks, invalid base64, oversized files), which the description leaves entirely to inference.

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 both parameters are fully documented in the schema, including filename's role in format detection. The description's '(base64-encoded bytes)' merely restates the schema and adds no syntax or format detail beyond it. 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?

States a specific verb (parse), the input formats (CSV or XLSX), the input encoding (base64 bytes), and the output (Markdown tables). This is clear and goes beyond the title, though it does not explicitly name or contrast with siblings like pdf_to_markdown or ocr_image — the format constraint implies the distinction rather than stating it.

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 by the accepted formats: an agent can infer this is the tool for spreadsheet inputs rather than PDFs, images, or URLs. However, there is no explicit when-to-use guidance, no statement of prerequisites, and no naming of the sibling alternatives.

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