read_image

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

Annotations already cover safety (readOnly, idempotent, non-destructive), so the bar is lower, and the description still adds real behavioral value: the normalization pipeline (SVG rasterization, downscaling above maxDimension, PNG/JPEG re-encoding). It omits failure modes (unreachable URL, unsupported/unreadable file, oversize base64), so not a full 5.

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?

Front-loaded with the core action and immediately followed by the mandatory workflow directive and the normalization behavior; nearly every clause is load-bearing. Slightly dense with the scraping-workflow instruction embedded, but no filler.

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?

No output schema exists, yet the description explains the return value (image content block the model can 'see'), all input sources, supported formats, and automatic transformations. For a 5-param, zero-required reader, an agent has everything needed to call it correctly.

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 coverage is low at 20% — only maxDimension is documented in the schema. The description compensates partially by mapping the three source parameters (path/url/base64) and implying mimeType via the format list, but gives no syntax or format details for `data`/`url`/`path`, so the gap is only partly closed.

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 (load/read), the resource (image), enumerates supported formats, lists the three input sources (path/url/base64), and names the exact return shape (vision-ready MCP image content block). An agent can distinguish this from read_pdf/read_text_file/inspect_file immediately.

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?

Gives an explicit when-to-use directive ('REQUIRED after scraping a website: call this with url= on every high-value photo') plus an anti-pattern exclusion ('Do not skip this and dump unlabeled URLs'). The condition that selects this tool versus text-based readers is unambiguous.

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