NEXO Brain

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

With no annotations provided, the description carries the full burden. It discloses that the tool performs registration and cleanup operations (implying mutation), returns data, and has a session ID that must be stored for other tools. However, it doesn't mention potential side effects like data persistence, authentication requirements, or error conditions. The description adds some behavioral context but leaves gaps for a tool with mutation capabilities.

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 extremely concise and well-structured: two sentences that efficiently communicate the tool's purpose, usage pattern, and output handling. Every word earns its place, with no redundant information. The most critical information (call once at start) is front-loaded in the second sentence.

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?

Given that there's an output schema (which handles return values), no annotations, and a simple single-parameter input schema, the description provides good contextual completeness. It explains the tool's role in the ecosystem, when to call it, and what to do with the output. The main gap is lack of behavioral details about the cleanup operation's impact, but the output schema reduces the need to describe return values.

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 input schema has 1 parameter with 0% description coverage, and the description provides no parameter information. However, since there's only one optional parameter with a default value ('task': 'Startup'), the tool can be used effectively without parameter knowledge. The description compensates by focusing on usage patterns rather than parameters, making it reasonably complete despite the schema gap.

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 clearly states the tool's purpose: 'Register new session, clean stale ones, return active sessions + alerts.' This specifies the verb (register/clean/return) and resources (sessions/alerts). However, it doesn't explicitly differentiate from sibling tools like 'nexo_status' or 'nexo_heartbeat' which might also provide session information, so it doesn't reach the highest score.

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 provides explicit usage guidelines: 'Call this ONCE at the start of every conversation.' This clearly states when to use it (start of conversation) and implies when not to use it (later in conversation). It also mentions storing the session ID for use in other nexo_ tools, establishing its foundational role.

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