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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds real behavioral value beyond that: it describes the shape of the returned entries and what full:true changes (every diagram's messages and payloads in one Markdown document). It omits any note on pagination, size limits or error behavior for a bad id.

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?

Two tightly packed sentences: the first front-loads what is returned, the second covers the routing to describe_diagram and the full mode. Every clause earns its place with 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?

With no output schema, the description carries the burden of explaining the return value and does so thoroughly, including the alternate full-mode output format. For a two-parameter read-only tool this is complete enough for an agent to invoke 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 description coverage is 100%, so the baseline is 3, but the description goes further by explaining that full:true returns messages and payloads as a single Markdown document and why (as context before writing integration code) — meaning the schema's terse 'Include every diagram's messages and payloads' does not fully capture.

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 (Read) and a precisely scoped resource (one of your collections, by id), then enumerates exactly what comes back: description and every entry in order with scenario name, diagram id, title and usage note. This clearly distinguishes it from list_collections and get_diagram without the agent needing to open a 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?

Explicitly states the use case ('use it to pick the right pattern for a scenario') and routes the agent to the next tool ('then describe_diagram with that id for the details'), plus the full:true workflow before writing integration code. It gives clear when-to-use context but no explicit when-not or negative conditions.

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