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

Annotations are minimal (readOnlyHint=true, destructiveHint=false), so the description carries the full burden. It reveals key behaviors: conversion happens on Microsoft's servers (no local re-encoding), the result is stored at a durable Hermoso URL, Microsoft's own link expires quickly (warning not to share it), and it requires OneDrive connected but asks for no new permissions. This adds substantial context beyond the annotations and helps the agent understand side effects and output properties.

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 description is longer than minimal but every sentence earns its place. It front-loads the core purpose, then provides supporting context (format support, use cases, critical requirement, output URL behavior). The structure is logical, with the most important constraints (JPG dimensions, durable URL) clearly highlighted. Slightly verbose but justified by the tool's complexity.

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?

Given the tool's complexity (4 params, no output schema but describes output URL, broad format support), the description covers all critical aspects: what it does, when to use it, parameter requirements, output characteristics, and prerequisites (OneDrive connected). An agent has everything needed to invoke it correctly without additional research. Failure modes are not detailed, but that's not a requirement for this scoring.

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?

With 100% schema description coverage, baseline is 3, but the description adds meaning: it explicitly states that JPG REQUIRES both width and height, clarifies fileId comes from list_onedrive_files, and notes format defaults to pdf. These are non-obvious details that prevent common errors. The description goes beyond mere schema documentation.

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 opens with a clear verb+resource: 'Turn a file already in the user's OneDrive into a PDF or a JPG.' It also specifies the exact output formats and differentiates itself by highlighting the broad format support (PSD, raw camera formats, etc.) that nothing else in the product can open. This distinguishes it from related tools like get_onedrive_file or generate_image without ambiguity.

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?

Explicit use cases are given: 'turn a client's deck into images... get a usable JPG out of a designer's PSD... hand someone a PDF of a spreadsheet.' It also explains why it's the right tool for these scenarios ('the point is the 130 source formats'). While it doesn't explicitly name alternatives or when-not-to-use, the context strongly implies its niche and conveys critical usage constraints (e.g., JPG requires both width and height). The guidance is clear and actionable.

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