session_info

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

No annotations exist, so the description carries the full burden. It does add genuinely useful behavioral detail beyond a bare name: the token is masked (a security-relevant fact) and the login state is authoritative enough to skip re-authentication. However, it never states that the call is read-only/side-effect free, nor how fresh or cached the status is.

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?

A single dense sentence plus a short conditional note — well front-loaded and free of filler. Slight deduction because 'Router status' and 'declared coordinator (`native_tools`)' are compressed to the point of near-opacity for a reader without prior context.

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 and no annotations, the description must effectively serve as the return-value contract, and it does by listing the fields returned. What remains unexplained is the semantics of the values (what 'router status' states exist, what a 'declared coordinator' means in practice), which an agent may need to interpret results.

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 tool takes zero parameters, so there is nothing to document and the baseline of 4 applies. The description appropriately spends no space on inputs.

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 enumerates exactly what the tool surfaces: router status, login state and account, masked token, MCP version, and declared coordinator. That gives an agent a concrete picture of the resource being inspected, and the trailing note about logged_in=true hints at its relationship to the `login` sibling. It never states a verb ('returns'/'inspect'), so the purpose is inferred from the field list rather than declared.

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 only usage signal is implicit: 'logged_in=true: no need to log in again' suggests checking this before calling `login`. There is no explicit statement of when to call it (e.g., at session start), no mention of alternatives like `connect_info` or `get_preferences`, and no exclusions.

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