session_read

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

Annotations already declare readOnlyHint=true and destructiveHint=false. The description adds value beyond those annotations by disclosing the exact not_found error shape for unknown sessions and characterizing the file as 'thin' rather than a full session object. No contradiction with annotations is present.

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?

Three tight sentences with no filler. The core operation is front-loaded, followed by the error behavior and read-only confirmation. Every sentence contributes useful information, and the 'Read-only' sentence, while redundant with annotations, is short and non-harmful.

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 two-parameter read with no output schema, the description covers the operation, the content of the state file, and the unknown-session error path. A fully explicit success return envelope is not described, but the listed file contents imply what a successful read returns, so the definition is reasonably complete.

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 coverage is 0%, so the description must compensate for the two undocumented parameters. It only paraphrases them as 'app/session pair' and does not explain format, meaning, or any constraints beyond their obvious roles. The schema supplies only titles, so the description adds minimal semantic value for invoking the tool correctly.

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?

States a specific verb ('Read'), a precise resource ('thin per-session state file'), and the file's contents (entry mode, bound dispatch, project/workspace). It also names the related writer (session_enter), making the tool's role unambiguous and distinct from write-oriented session siblings.

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 clear context: use this to read the per-session state written by session_enter. It does not explicitly list exclusions or compare with alternative readers, but the relationship to session_enter and the 'Read-only' framing provide enough guidance for an agent to select it appropriately.

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