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

Annotations already cover readOnly/idempotent/non-destructive, and the description adds substantial context beyond them: the auth requirement, the hard boundary that this connector cannot publish or save, and most importantly the identity-stamping behavior of the `line9:` frontmatter that must be preserved to avoid creating a duplicate diagram on publish.

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?

Purpose is front-loaded in the first sentence, and the follow-on sentences earn their place by covering the frontmatter contract, auth, and publish boundary. It is somewhat dense with workflow/CLI tangents, but there is little redundancy.

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 single-parameter read tool with an output schema (which the description correctly does not duplicate), the definition covers the auth prerequisite, prohibited actions, and the crucial frontmatter-preservation rule an agent needs to act correctly. Nothing material is missing.

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 100%, so the single `diagram` parameter is fully documented by the schema (name, slug, or trailing public_ref). The description merely echoes 'by name or slug', adding no new meaning and actually omitting the public_ref option the schema lists, so the baseline 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 first sentence gives a specific verb and resource: fetch a published diagram's Mermaid source by name or slug and show it rendered. That clearly separates it from list_diagrams, and implicitly from render_diagram (fetch vs. render-a-given-source), though no sibling is named explicitly.

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?

The description gives real context — Line9 sign-in is required, this connector cannot publish or save, and publishing happens in the Line9 web UI via open_url rather than the CLI. However, it never states when to choose get_diagram over render_diagram or list_diagrams, so tool-selection guidance is only implied.

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