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

With no annotations, the description carries the full burden and does well: it discloses the algorithm, the return shape (good matches as point pairs sorted by distance), scaling/rotation tolerance, and pricing ($0.004 per call). It omits auth/permission requirements and rate limits, so it is strong but not exhaustive.

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 front-loaded with the core action and mechanism, then the usage note and pricing, with no filler sentences. It is dense with technical terms but each clause conveys useful information for invocation.

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 six-parameter tool with no annotations and no output schema, the description covers the operation, algorithm choice, result format, scaling/rotation behavior, sibling alternative, and cost. Only peripheral details (auth, rate limits) are absent, so it is largely complete.

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 all six parameters, including the ratio, detector enum, max_matches, and max_features semantics. The description largely restates this (Lowe's ratio test, ORB vs SIFT) rather than adding new parameter meaning, so the baseline of 3 applies.

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 states a specific verb+resource (match local features between a pattern and a larger image) and details the mechanism (ORB/SIFT keypoints, BFMatcher.knnMatch, Lowe's ratio test) and output (point pairs sorted by distance). It also explicitly differentiates from the homography sibling for the pattern's outline, so an agent can distinguish it 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?

It gives a clear use context ('see which parts of a pattern are present and where, even when the pattern is scaled or rotated') and routes to /v1/homography for outlines. However it never mentions the template-match sibling, which is the most likely alternative for a matching task, leaving a gap in when-not-to-use guidance.

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