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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds genuinely new behavior beyond those annotations: the 512 KB ceiling and refusal of binary files, which are the likely runtime failure modes. It does not describe error behavior for missing files, but that is a minor gap.

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?

Two sentences with zero waste: the action is front-loaded, and the hard constraint plus workaround follow immediately. Every clause earns its place; there is no repetition of schema or annotation content.

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, the description properly discloses the return value ('return its contents') and the critical constraints. For a simple read tool whose safety profile and parameters are already documented, this is nearly complete; only minor omissions like encoding or failure behavior prevent a 5.

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 description coverage is 100% — host ('Server id from hosts_list'), path ('Absolute or home-relative file path'), and username ('Login user...defaults') each carry meaning. The description adds no parameter-level detail beyond implying path points to a text file. Baseline 3 is correct when the schema does the heavy lifting.

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 resource ('text file from one of your servers over SFTP'), and the result ('return its contents'). The 512 KB / binary-file refusal distinctly separates it from siblings like sftp_write, sftp_list, and especially ssh_exec without needing to inspect any schema. The title 'Read a file' is consistent and adds nothing contradictory.

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?

Gives an explicit when-not-to-use condition ('Files over 512 KB or non-text (binary) files are refused') and names the alternative with concrete command examples ('use ssh_exec (e.g. sed/tail)'). An agent can route correctly without inference.

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