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

Annotations already declare readOnlyHint=true and destructiveHint=false, so no safety contradiction exists. The description adds substantial behavioral context: it clarifies these are created/existing integrations, explains the optional project_id behavior, lists the exact response fields and wrapper, and tells the agent that integrationId maps to marketplace_id in other tools. This goes well beyond what annotations provide.

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 dense but every sentence earns its place. The core distinction from list_marketplace_channels is front-loaded, and the subsequent sentences cover return shape, parameter behavior, error handling, and cross-tool ID mapping. Given that there is no output schema, the field enumeration is justified rather than 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?

For a simple read-only list tool with one optional parameter and no output schema, the description is complete. It covers the purpose, the sibling distinction, parameter semantics, error behavior, response structure, and how results relate to other tools. Nothing an agent needs to call it correctly 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 description coverage is 0%, so the description carries the full explanatory burden for the single parameter. It thoroughly defines project_id semantics: optional, what happens when provided vs omitted, and how to recover from the project_id_required error. This adds meaning far beyond the bare integer type in the schema.

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 and resource: list the already-created marketplace integrations of a project. It explicitly distinguishes itself from list_marketplace_channels, which is the catalog of channels that can be added, so there is no ambiguity about scope. The phrasing is specific and not a tautology.

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 explicit usage guidance: pass project_id to get a specific project's marketplaces, omit it to get all projects' marketplaces. It also names the alternative tool (list_marketplace_channels) and tells the agent when to use that instead. It even handles an error condition (project_id_required) with a concrete remedy.

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