project_join

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

The description discloses key behavioral traits beyond the annotations: it replaces the previous membership, makes project-scoped memory and tasks visible, and sets unqualified writes to default to this project. These are meaningful side effects that are not covered by idempotentHint or destructiveHint. This adds substantial value for an agent deciding to use the tool.

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 well-structured: a direct first sentence states the core action, followed by a concise explanation of behavioral implications and a clear Args block. It is slightly verbose for a simple tool, but each sentence contributes to understanding the behavior and usage. The important information is front-loaded, making it easy to parse.

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?

The description covers the purpose, usage timing, and behavioral consequences adequately. Since an output schema exists and is referenced, the description does not need to explain return values. For a single-parameter tool, it provides sufficient context for correct invocation without missing critical details.

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?

The schema already documents project_id as 'The project name to switch to,' and the description repeats this in the Args section without adding further semantics. With 100% schema coverage, the baseline of 3 applies. The description does provide contextual usage around the parameter, but it does not enrich its meaning beyond 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 explicitly states 'Switch to a project, this becomes your single active project,' which clearly identifies the verb and resource. It also explains the effect of replacing previous membership, making it unambiguous and distinct from siblings like project_leave or project_list. This directly addresses what the tool does and differentiates it from related actions.

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: 'Join the project you're working in at session start.' It also implies when to use it for switching projects and clarifies the one-active-project model. While it does not explicitly name alternatives, the context is clear enough for an agent to infer when to invoke this tool versus project_leave or project_list.

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