context_stats

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

With no annotations, the description carries the full burden of behavioral disclosure. It reveals methodology ('real tokenizer'), scope ('exactly what this server sent'), and the price assumption (LOSSLESS_PRICE_PER_MTOK, default $3/MTok). It does not explicitly state read-only safety, but the nature of stats reporting makes that implicit.

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 two sentences, front-loaded with an engaging question, and each clause adds substantive detail (breakdown types, pricing, tokenizer). No filler or 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 no-parameter, no-output-schema tool, the description fully specifies what is reported and how it is computed. The agent can infer the return types (counts, USD amounts, file paths) and the scope (session file-read tokens) without ambiguity.

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 zero parameters, so the description need not explain parameters. It adds context about an environment variable (LOSSLESS_PRICE_PER_MTOK) which is relevant to the output, exceeding the schema's empty property list.

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: 'Where did this session’s file-read tokens go?' and enumerates specific outputs (totals, per-repo breakdown, heaviest files, dedup savings, USD estimate). This makes it distinct from the sibling tools, which focus on reading files or context receipts.

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 clear context: this tool is for analyzing file-read token consumption within the current session. It does not explicitly mention alternatives or when-not-to-use, but the purpose is self-evident and adequately guides selection among the listed siblings.

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